JP4289665B2 - Reactor, reactor core and manufacturing method thereof - Google Patents

Description

【００９５】
【表２】

【図面の簡単な説明】
【図１】リアクトル用コアを構成する一つの圧粉成形体の断面形状を示す図である。
【図２】本発明に係るリアクトル用コアの一形態を示す平面図であり、同図（ａ）は直方体状の圧粉成形体を組合わせたものであり、同図（ｂ）は直方体状の圧粉成形体とＵ字状の圧粉成形体とを組合わせたものである。
【図３】図２（ａ）に示したリアクトル用コアの斜視図である。
【図４】各試験片毎の交流抵抗値を示す棒グラフである。
【符号の説明】
１〜３ ブロック
５ 樹脂板
１０ コア
２０ コア[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reactor used in a power supply circuit and the like, a core (magnetic core) used in the reactor, and a method for manufacturing the reactor core.
[0002]
[Prior art]
In industrial machines, household electrical appliances, electric vehicles, hybrid vehicles, etc., conversion between a DC power supply and an AC power supply, voltage conversion between DC power supplies (DC-DC conversion), etc. are performed via a switching power supply or the like. . For example, in the case of an electric vehicle or a hybrid vehicle, the voltage is reduced from the voltage of the storage battery (200 to 300 V) to the voltage for vehicle electrical components (12 to 48 V). In addition, when inverter control is performed on a brushless motor or the like, a DC power source is converted into a high frequency AC power source.
[0003]
A power supply circuit constituting such a switching power supply is provided with a reactor including a core (iron core) and a coil in which a copper wire or the like is wound around the core. In addition, even if it combines a core and a coil similarly, although a name changes suitably with the use and function, in this specification, they are collectively called a reactor.
[0004]
Although the required performance varies depending on the application, the reactor is generally required to have a small size, low loss, low noise and excellent direct current superposition characteristics. For example, a core having high saturation magnetization is used to reduce the size of the reactor, and a core having high specific resistance and low coercive force is used to reduce loss. In order to improve the direct current superimposition characteristic, a core having a stable inductance (L), specifically a core having a stable magnetic permeability (constant magnetic permeability) is desirable.
[0005]
Thus, in order to improve the performance of the reactor, the performance of the core disposed in the coil is very important. For this reason, a wide variety of cores having been appropriately changed in material, manufacturing method, form, and the like have been used depending on the application of the reactor.
[0006]
For example, the core material includes oxide ferrite, Fe-Si steel plate, amorphous ribbon, and the like. The core using these is manufactured by laminating plate materials, compacting, compacting and the like. Further, a plurality of block-shaped cores having a predetermined shape are joined to form a core having a desired shape, or an apparent air permeability is adjusted by providing an appropriate gap (gap).
[0007]
More specifically, a core made of an amorphous ribbon is used for a high current (high power) reactor, and an Fe-Si steel plate is often used for a low frequency (several kHz or less) reactor. A dust core is used for the power factor improving choke coil, and the powder is often composed mainly of Fe-7% Si or Sendust (Fe-9% Si-6% Al).
[0008]
Further, patent documents relating to such a reactor core include the following. Patent Document 1 describes that transformer cores of various shapes can be easily manufactured by joining bulk bodies formed by high-density molding of Fe-based soft magnetic alloy particles. Patent Document 2 describes a dust core for a reactor that can improve the efficiency of a switching power supply having a frequency of 10 kHz or more.
[0009]
[Patent Document 1]
JP-A-5-326289
[Patent Document 2]
JP 2002-75719 A
[0010]
[Problems to be solved by the invention]
By the way, a core made of an amorphous ribbon is expensive because it requires a special manufacturing apparatus for its production, and has a large magnetostriction and a large noise. Since the ferrite core has a low saturation magnetization, DC superposition characteristics are poor in a large-capacity power supply, and the volume (cross-sectional area) needs to be increased to compensate for the shortage of magnetic flux, leading to an increase in size of the component.
[0011]
In the core made of the Fe—Si based electromagnetic steel sheet, the loss rapidly increases when the frequency used is about 20 kHz or more, so that the frequency range used is limited to that. In addition, when a high current is applied to the coil, it is necessary to increase the saturation magnetic flux density or improve the DC superposition characteristics by providing a gap (see Patent Document 1) in a part of the magnetic path. In any case, however, the noise becomes large.
[0012]
In the case of a core (powder magnetic core) formed by compacting Fe-Si powder or the like whose particle surface is insulated, the magnetic flux density can be increased by increasing the density, and the powder particles are covered with an insulating coating. High specific resistance and low eddy current loss. However, the DC superposition characteristics when a high current is applied to the coil are still poor, and the inductance on the high current side is likely to be significantly reduced. In order to improve the direct current superposition characteristics, it is considered effective to increase the saturation magnetic flux density or to provide a gap or the like in a part of the magnetic path. However, such a countermeasure is not preferable because it results in an increase in loss. Details of this will be described later.
[0013]
Furthermore, the dust core for reactor of the said patent document 2 does not respond | correspond to the high electric power to which the high current of 100 A or more is superimposed and applied, for example, and also with the reactor corresponding to the high ripple current in several to several tens of kHz Absent.
[0014]
From this point of view, a reactor and a reactor core that are low loss, low noise, small size (about several kg), and that can handle high power and high ripple current are desired. If a special Si steel plate (thickness: 0.05 mm), inclined Si steel plate (thickness: 0.05 to 0.1 mm), amorphous ribbon, etc. are used, it may be possible to make such a reactor. Although it is not practical because it is very expensive, and even in that case, the noise is still large.
[0015]
The present invention has been made in view of such circumstances, and an object of the present invention is to provide a reactor that can be used for high power with a large current superimposed thereon and that can achieve loss reduction, noise reduction, miniaturization, and the like. To do. Moreover, it aims at providing the core for reactors suitable for the reactor, and its manufacturing method collectively.
[0016]
[Means for Solving the Problems and Effects of the Invention]
  As a result of extensive research and trial and error, the present inventor has found a reactor core that has high saturation magnetization and excellent direct current superposition characteristics, can reduce overall loss, and can be downsized. Based on this, the reactor of the present invention was completed.
(Reactor)
(1) That is, the reactor of the present invention is a soft magnetic powder containing Fe as a main component.The particle surface of the soft magnetic powder is coated with an insulating coatingA reactor consisting of a reactor core formed by combining at least two compacted compacts obtained by compressing raw material powder, and a coil wound around a conducting wire and attached to the reactor core,
  The green compact has a true density (ρ ₀ ) Is the ratio of the bulk density (ρ) to the density ratio (ρ / ρ ₀ :%) Is 90% or more,
The core for reactor has a non-magnetic material having a width of 4 mm or less different from the insulating coating at one or more positions between opposed surfaces where each of the combined powder compacts is abutted.
  A saturation magnetization of the reactor core is 1.7 T or more, and a first apparent magnetic permeability (μ) obtained when a magnetic field of 5 kA / m is applied to the reactor core._5k) Is 25 or more and the second apparent permeability (μ) obtained when a magnetic field of 35 kA / m is applied._35k) Is the first apparent permeability (μ_5k), And an AC resistance value (r) at the time of mounting, which is an AC resistance value of the coil obtained when 10 mA of alternating current of 10 kHz flows through the coil in a state where it is mounted on the reactor core.₁) Is a single-unit AC resistance value (r) that is an AC resistance value of the coil obtained when 10 mA of AC is applied to the single coil that is not attached to the reactor core.₀) Less than 2.5 times (r₁≦ 2.5r₀).
[0017]
In the reactor of the present invention, the core on which the coil is mounted is formed by combining a plurality of powder compacts obtained by compacting raw powders of soft magnetic powder and insulating material. Appropriately adjust the composition of the soft magnetic powder constituting the green compact, the material or blending amount of the insulating material, etc., and appropriately select the spacing between the facing surfaces of the green compact to be combined and the inclusions interposed therebetween Thus, a reactor having the saturation magnetization, the apparent permeability, and the AC resistance value is obtained.
[0018]
In the case of the reactor of the present invention, first, the saturation magnetization of the core is as high as 1.7 T or more, and the apparent permeability is kept stable even in a high magnetic field such as 5 kA / m or 35 kA / m. For this reason, a reactor having excellent direct current superimposition characteristics can be obtained. If this reactor is used, a switching power supply having a stable output can be obtained even when a large current is applied to the coil. Moreover, a reactor corresponding to a high ripple current is obtained, and noise is also suppressed.
[0019]
Next, the compacting body which forms the core for reactors of this invention consists of a powder particle each insulated with the insulating material. For this reason, a specific resistance is also large and the iron loss (high frequency loss) which arises with the compacting body is also small.
[0020]
Here, according to the research of the present inventors, it is clear that it is very effective to reduce not only the iron loss that has been regarded as a problem but also the copper loss of the coil itself in reducing the loss of the reactor. It became. In the present invention, the material of the conductive wire constituting the coil is not limited. For convenience, the loss in the coil is called copper loss, and is distinguished from high-frequency loss (iron loss) generated in the reactor core. By the way, iron loss mainly consists of eddy current loss and hysteresis loss.
[0021]
Detailed investigations by the inventor have revealed that copper loss is affected by the properties of the core. And it became clear that this copper loss will increase, if the compacting body which comprises a core is increased in density very much in order to increase magnetic flux density. On the other hand, when the specific resistance of the green compact was increased, it was also clarified that this copper loss was reduced. The reason why such a phenomenon occurs is not necessarily clear, but at present, it is considered as follows. That is, when the specific resistance value of the green compact is low, an eddy current is likely to be generated, and this eddy current is linked to the coil to prevent the current flowing through the coil.
[0022]
By the way, this copper loss is naturally a loss when the coil is mounted on the core, and depends on the AC resistance value at each frequency and the current value flowing at that time. For this reason, in order to reduce copper loss, it is effective to reduce the AC resistance value of the core when the coil is attached to the core. This AC resistance value varies depending not only on whether the coil is attached to the core but also on the frequency and current (voltage) value of the applied current. Therefore, in the present invention, for the sake of convenience, the evaluation was made based on the AC resistance value when an alternating current of 10 kHz was passed through the 10 mA coil. Then, as a range in which the copper loss can be effectively reduced, the AC resistance value at the time of mounting, which is the resistance value when the coil is mounted on the core, is defined as 2.5 times or less of the AC resistance value at the time of single coil. As described above, if the AC resistance value at the time of mounting is approximately the same as the AC resistance value at the time of the single unit, the loss generated in the reactor can be reduced even when the applied AC current value is increased.
[0023]
Thus, the reactor of the present invention can be downsized because the core has a high saturation magnetization, and the apparent permeability is stable up to a high magnetic field, so it has excellent direct current superposition characteristics, for example, several to several tens of kHz ( For example, it is possible to cope with a high ripple current of 1 to 100 kHz and noise is suppressed. Further, since the AC resistance value is small when the coil is mounted, the loss of the entire reactor is very small. Therefore, although the reactor of the present invention can be used for high power, it is small, low noise, and highly efficient with little loss.
[0024]
By the way, in the case of the reactor of this invention, it is preferable if the said saturation magnetization becomes 1.8T or more, 1.9T or more, and 2.0T or more. If the saturation magnetization is too small, it is not preferable because the DC superimposition characteristics deteriorate and the performance of the reactor decreases, but conversely, if the saturation magnetization becomes excessive due to high density forming, the copper loss increases as described above. The upper limit is preferably 2.0T. In addition, the apparent permeability is the first apparent permeability (μ_5K) Is 25, 30, 35 or more, the second apparent permeability (μ_35K) Is the first apparent permeability (μ_5K70, 80, 90% or more of If the apparent permeability is too low, sufficient inductance cannot be obtained and the performance of the reactor will decrease, but conversely, even if the apparent permeability is excessive, the DC superimposition characteristics will deteriorate and the performance of the reactor will deteriorate. Therefore, the upper limit is preferably 50. Further, the AC resistance value when mounted is preferably 2.3 times or less, 2.1 times or less, and 2.0 times or less of the AC resistance value when single. AC resistance value (r₁Specifically, for example, it is preferably 1Ω or less, 0.9Ω or less, or 0.8Ω or less.
[0025]
(2) The reactor of the present invention is specified by the characteristics as described above, for example, as follows.
  That is, the present invention provides a soft magnetic powder mainly composed of Fe.The particle surface of the soft magnetic powder is coated with an insulating coatingA reactor core configured by combining at least two compacts formed by compressing raw material powder;
  A reactor comprising a coil wound around a conducting wire and attached to the reactor core,
  The green compact has a true density (ρ₀) Is the ratio of the bulk density (ρ) to the density ratio (ρ / ρ₀:%) Is 90% or more, and the reactor core is combined between the opposing surfaces of the green compact that forms a magnetic path.More than one placeInDifferent from the insulating coatingLess than 4mm in widthNon-magnetic materialIs interposed, and the coil may be a reactor in which a rectangular copper wire is wound for 30 turns or more. In addition, the cross-sectional area of this rectangular copper wire may be appropriately selected according to the use conditions (frequency, superimposed current, inductance, etc.) of the reactor so that the coil is not significantly damaged thermally by copper loss during use. It is preferable.
[0026]
In the reactor of the present invention, the above-described characteristics are expressed by specifying the amount of insulating material in the green compact, the density ratio thereof, and the state between the opposing surfaces of the green compact to be combined as described above. A reactor core and reactor are obtained.
[0027]
(Reactor core)
  This invention can be grasped | ascertained not only as said reactor but as a reactor core which comprises it.
  That is, the present invention provides a soft magnetic powder mainly composed of Fe.The particle surface of the soft magnetic powder is coated with an insulating coatingA core for a reactor configured by combining at least two compacts formed by compressing raw material powder,
  The green compact has a true density (ρ₀) Is the ratio of the bulk density (ρ) to the density ratio (ρ / ρ₀:%) Is 90% or more, and between the opposing surfaces of the green compact that is combined to form a magnetic pathMore than one placeInDifferent from the insulating coatingLess than 4mm in widthNon-magnetic materialIt is good also as a core for reactors characterized by being interposed by one or more places.
[0028]
(Reactor core manufacturing method)
  The reactor core is manufactured as follows, for example.
  That is, the present invention provides a soft magnetic powder mainly composed of Fe.The particle surface of the soft magnetic powder is coated with an insulating coatingA method for producing a reactor core comprising a combination of at least two compacts of compacted raw material powder,
  The green compact isA filling step of filling the raw material powder into a molding die coated with a higher fatty acid-based lubricant; and the raw material powder filled in the molding die is warm-pressed and A molding step of obtaining a powder compact by forming a metal soap film on the surface of the soft magnetic powder in contact with the inner surface of the molding die;Manufactured byTrue density of the soft magnetic powder (ρ₀) Is the ratio of the bulk density (ρ) to the density ratio (ρ / ρ₀:%) Is 90% or moreIn addition, the plurality of dust compacts are formed by interposing a non-magnetic material different from the insulating coating having a width of 4 mm or less at one or more locations between the opposing surfaces formed when the obtained plurality of compact compacts are butted. Combine the body into a reactor coreIt is good also as a manufacturing method of the core for reactors characterized by these.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
Next, the present invention will be described in more detail with reference to embodiments. It should be noted that the contents described in this specification including the following embodiments are applicable not only to the reactor of the present invention but also to the reactor core and the manufacturing method thereof as appropriate.
(1) Soft magnetic powder and insulating material
The soft magnetic powder according to the present invention is a powder containing Fe as a main component, but preferably contains 2 to 5% by mass of Si. Si is an element effective in increasing the electrical resistivity (specific resistance) of the powder particles and reducing the eddy current loss of the green compact. Moreover, the core which combined the compacting body which consists of Fe-Si type powders is excellent in a direct current | flow superimposition characteristic. Here, if the Si amount is less than 2% by mass, the loss increases. On the other hand, if the amount of Si exceeds 5% by mass, the magnetic flux density of the green compact is reduced, which is not preferable. It is more preferable that the lower limit of the Si amount is 2.5 mass% and 3 mass%, and the upper limit is 4.5 mass% and 4 mass%.
[0030]
This soft magnetic powder may be composed of such Si, the balance being Fe and inevitable impurities, and may contain an element for improving magnetic properties or an element for reducing iron loss as appropriate. Examples of such elements include aluminum (Al), nickel (Ni), and cobalt (Co).
[0031]
The soft magnetic powder according to the present invention preferably has a weight average particle size of 30 to 70 μm. . The weight average particle diameter is a particle diameter determined from the particle diameter when the weight reaches 50%, integrated from fine particles.
[0032]
If the weight average particle size (hereinafter also simply referred to as “particle size”) is less than 25 μm, the eddy current loss is reduced, but the hysteresis loss is excessively increased. Conversely, if the particle size exceeds 100 μm, the hysteresis loss decreases, but the eddy current loss increases excessively, which is not preferable. When a soft magnetic powder having a particle size in the above range is used, a green compact that can sufficiently reduce the iron loss, which is the sum of eddy current loss and hysteresis loss, is obtained in the above-described low and medium frequency ranges. . More preferably, the lower limit of the weight average particle diameter is 35 μm, 40 μm, and 45 μm, and the upper limit is 65 μm, 60 μm, and 55 μm.
[0033]
The soft magnetic powder according to the present invention preferably has an average aspect ratio of 1 to 3. . The average aspect ratio is an average value of the ratio (aspect ratio) between the maximum diameter (major axis) and the minimum diameter (minor axis) of the powder particles. This average value may be obtained by observing a large number of powder particles with an SEM and image analysis. In the case of the present invention, the closer the average aspect ratio (hereinafter also simply referred to as “aspect ratio”) is to 1, that is, the more the powder particles are spherical, the lower the coercive compact. Reduction of the coercive force of the green compact is effective in reducing hysteresis loss. Furthermore, the closer the aspect ratio is to 1, the larger the specific resistance, which is effective in reducing eddy current loss. Therefore, the aspect ratio is preferably closer to 1, and the upper limit is more preferably 2.5, 2, 1.5, or the like.
[0034]
Here, the closer the average aspect ratio is to 1 (that is, the closer the shape of the powder particles is to a spherical shape), the smaller the coercive force of the green compact, and the larger the specific resistance is considered as follows. It is done. If the powder particles are close to a spherical shape, the aggression between the particles in contact with each other is reduced when the soft magnetic powder is pressed. On the other hand, if there are many particles having a large aspect ratio and a distorted shape, the projections of one particle pierce other adjacent particles by the pressure applied during molding. And it seems that a large strain or stress is applied only to a very small part of the particle, resulting in an increase in coercive force. In addition, as a result of the increased aggression between particles as described above, the insulating coating formed on the surface of each particle is also easily broken, and the portion where each particle is in direct contact is increased, reducing the specific resistance. Seem.
[0035]
Furthermore, the soft magnetic powder according to the present invention preferably has a coercive force (iHc) of the powder particles of 200 A / m or less. . Since the coercive force of the soft magnetic powder used from the stage before pressure molding is small, the coercive force of the obtained powder compact is also small. Thereby, the compacting body with small hysteresis loss and excellent magnetic characteristics is obtained. This iHc is more preferably 180 A / m or less, 160 A / m or less, and even 150 A / m or less. Such a soft magnetic powder having a low coercive force can be easily obtained, for example, by subjecting an atomized powder or the like to heat treatment to remove residual stress, distortion, or the like. Therefore, the soft magnetic powder is preferably heat-treated at 800 ° C. or higher in an inert atmosphere before pressure molding. The inert atmosphere may be a vacuum atmosphere, an inert gas atmosphere, or a reducing atmosphere such as a hydrogen atmosphere. That is, it is preferable that the atmosphere is not an oxidizing atmosphere.
[0036]
Further, it is preferable that the particle diameter is as described above, and the number of crystal grains in one powder particle is 10 or less on average. The coercive force that affects the hysteresis loss depends on the outer shape of the powder particle itself, but also on the structure inside the powder particle. And the larger the structure is, the smaller the coercive force, and the easier it is to reduce the hysteresis loss. Assuming the above-mentioned weight average particle diameter, the average number of crystal grains in the powder particles is 10 or less, more preferably 8 or less and 5 or less. The average number of crystal grains may be obtained by embedding powder particles in a resin and observing the structure with an optical microscope.
[0037]
The method for producing the soft magnetic powder as described above is not limited. For example, it is also conceivable to obtain a powder by grinding an alloy ingot with a ball mill or the like. However, in order to obtain a more spherical powder, the atomization method is preferable. That is, a gas spray atomizing method in which gas is sprayed onto a molten metal stream having a predetermined composition to atomize, a water spray atomizing method in which water is sprayed onto the molten metal stream to atomize, and further, the molten metal stream is mixed with gas and water. It is preferable that the soft magnetic powder is produced by a gas / water atomizing method in which the mixture is atomized by spraying the mixture. In the present specification, the powders obtained by these atomizing methods are referred to as gas atomized powder, water atomized powder, and gas water atomized powder, respectively.
[0038]
When this inventor investigated, the atomized powder suitable for the compacting body of this invention was gas water atomized powder. This seems to be due to the relatively slow cooling rate. The gas used for the atomization method is preferably an inert gas such as N 2 or Ar.
[0039]
However, it is atomized in an oxidizing atmosphere and the surface of the powder particles is SiO.₂An appropriate insulating oxide film such as the above may be formed. This is preferable in that the specific resistance of the green compact is increased and eddy current loss can be reduced. However, SiO₂Etc. are hard, and if the amount is too large, the moldability of the soft magnetic powder is lowered, and the density of the green compact is reduced. In addition to this, the insulating film includes a resin film, a phosphate film, etc., but the oxide film is excellent in heat resistance, and is preferable because its breakage is suppressed and prevented even when heat treatment such as an annealing process is performed. . As such a heat-resistant oxide film, the SiO₂Besides, Al₂O_ThreeTiO₂, ZrO₂And their complex oxide insulating coatings.
[0040]
By the way, it is preferable that the compacting body of this invention positively contains the insulating material which insulates between the powder particles which comprise a soft magnetic powder separately from such an oxide insulating film. When the content of this insulating material increases, the magnetic flux density in the green compact decreases, which is not preferable, but by setting the content to 1 to 10% by volume, further 3 to 8% by volume, the magnetic flux density The desired magnetic permeability (apparent magnetic permeability) can be obtained even in a high magnetic field generated by a large current while suppressing the decrease of the above. And the reactor excellent in direct current | flow superimposition characteristic is obtained. Examples of such insulating materials include nitrides such as AlN and BN, minerals such as clay, silicone resins called binders (binding materials), amide resins, imide resins, phenol resins, and internal lubricants described later. Moreover, when a binder is used as an insulating material, an insulating film is easily formed.
[0041]
When the soft magnetic powder is warm-pressed as in the manufacturing method of the present invention described above, a new lubricant (excellent in lubricity) between the inner wall surface of the molding die and the soft magnetic powder ( A metal soap film) is formed. It has been found that this metal soap film exhibits the most excellent lubricity when it contains Fe (for example, an iron salt film of a higher fatty acid). Therefore, from the viewpoint of promoting the formation of such a coating, it is more preferable that the insulating coating itself contains Fe. Such an insulating coating is, for example, iron phosphate if it is phosphate-based, and FeSiO if it is oxide-based._Three, FeAl₂O_FourNiFe₂O_FourA complex oxide system such as Fe is desirable.
[0042]
As the film thickness increases, the specific resistance of the insulating film increases. However, if the film thickness is too large, the magnetic flux density of the formed green compact decreases. Therefore, from the viewpoint of securing the magnetic flux density and specific resistance of the green compact, the film thickness is preferably 1 to 1000 nm, and more preferably 10 to 100 nm.
[0043]
Needless to say, it is ideal that the insulating coating is originally formed for each of the powder particles. However, in practice, naturally, an insulating film may be formed around several particles in a solid state, and such a state is also assumed by the present invention.
[0044]
(2) Reactor core
The reactor core of the present invention is formed by combining compacted bodies obtained by high-density molding of the soft magnetic powder as described above.
First, the green compact has excellent magnetic properties such as magnetic permeability, saturation magnetization, and DC superimposition characteristics, and iron loss such as hysteresis loss and eddy current loss in a low to medium frequency range of 1 to 50 kHz. . These characteristics will be specifically described below.
[0045]
One index of the magnetic properties of the green compact is magnetic permeability, which varies depending on the strength of the magnetic field on which the green compact is placed. Therefore, the magnetic properties of the green compact are often indicated by the magnetic flux density when placed in a magnetic field having a specific strength. Magnetic flux density B generated when the green compact of the present invention is placed in a magnetic field of 10 kA / m, for example._10kThe magnetic flux density B_10kBecomes 1.1T or more, 1.2T or more, 1.3T or more, 1.4T or more, and further 1.5T or more.
[0046]
Saturation magnetization (Ms) is also an important index of magnetic properties. In the case of the green compact of the present invention, high saturation magnetization such as 1.8T or more, 1.85T or more, and 1.9T or more is exhibited. Due to such high saturation magnetization, a reactor core having excellent direct current superposition characteristics can be obtained. Needless to say, the saturation magnetization at this time is a saturation magnetization as a single compact body, and not a saturation magnetization as a whole core combining the same. The saturation magnetization is measured, for example, when the green compact is placed in a high magnetic field of 0.1 MA / m.
[0047]
Moreover, the compacting body of this invention also has a small coercive force. As a result, a reactor core having good followability to an alternating magnetic field and low hysteresis loss can be obtained. The coercive force of the green compact is, for example, 220 A / m or less, 200 A / m or less, and further 180 A / m or less. The iron loss of the green compact is, for example, 420 kW / m in an alternating magnetic field having a frequency of 10 kHz and a magnetic flux density of 0.2 T.^ThreeHereinafter, further 400 kW / m^Three380 kW / m below^Three350 kW / m^ThreeVery low such as:
[0048]
By the way, the magnetic properties such as the magnetic flux density of the green compact are greatly influenced by whether or not the high density molding is performed, that is, the density. However, since the density varies depending on the composition of the soft magnetic powder, the degree of high-density molding of the green compact cannot be indicated simply by the density alone. Therefore, in the present invention, the true density (ρ₀) To the density ratio (ρ / ρ), which is the ratio of the bulk density (ρ) of the green compact₀) To indicate the degree of high density molding. In the case of the green compact of the present invention, its ρ / ρ₀Has a density ratio of 92% or more, 93% or more, 94% or more, and 95% or more. However, the upper limit is preferably 95%. This is because if the density is too high, the AC resistance value increases and the loss increases.
[0049]
Next, there is a specific resistance as an index of the electrical characteristics of the green compact of the present invention. This specific resistance is an eigenvalue for each green compact that does not depend on the shape. If the green compact has the same shape, the larger the specific resistance, the smaller the eddy current loss. Since the green compact of the present invention is made of the specific soft magnetic powder described above, this specific resistance is relatively large, and the eddy current loss can be reduced accordingly. In the case of the green compact of the present invention, the specific resistance is 1000 μΩm or more, 10,000 μΩm or more, and further 100,000 μΩm or more. And as mentioned above, the coil of the reactor equipped with the core combined with this powder compact with a large specific resistance also has a small AC resistance value, which is effective in reducing the overall loss of the reactor.
[0050]
By the way, the reactor core of the present invention is formed by combining a plurality of the above compacted bodies. A plurality of compacted compacts can be butted and bonded together to form an integral reactor core. Moreover, you may fix a some compacting body with a fastener mechanically, without making it adhere | attach etc. FIG. However, no matter what combination is used, adjacent powder compacts have opposing surfaces facing each other, and this is usually the magnetic path. And it becomes possible to adjust the apparent permeability as the whole reactor core by devising the form between the facing surfaces. For example, the space between the opposing surfaces may be filled and bonded with an adhesive such as a thermosetting resin. Further, the gap between the opposing surfaces may be an air gap, or a resin material such as PPS (polyphenylene sulfide) may be interposed. For adjusting the apparent permeability, it is preferable to interpose such a non-magnetic material between the opposing surfaces. However, if the distance between the opposed surfaces is increased, the leakage magnetic flux and the like increase, and the performance of the reactor is reduced. Therefore, the distance between the opposed surfaces is preferably 4 mm or less, 3 mm or less, and more preferably about 0.5 to 2.5 mm. In addition to the form (shape, size, etc.) of the green compact, the form of the core formed by combining them is also arbitrary. What is necessary is just to determine suitably according to the required specification of a reactor.
[0051]
(3) Method for producing a green compact
The method for producing a green compact is basically composed of a filling step of filling a raw material powder composed of a soft magnetic powder and an insulating material into a molding die and a molding step of pressure-molding the filled raw material powder. .
[0052]
The green compact of the present invention does not exclude a raw material powder mixed with an internal lubricant and molded at room temperature and high pressure in a molding die. However, in this case, when the molding pressure is increased, galling is likely to occur between the inner surface of the molding die and the raw material powder, the pressure is excessively increased, or the mold life is extremely reduced. Regardless of the test level, considering the industrial level, it is actually difficult to increase the molding pressure in conventional mold molding, and as a result, it is difficult to obtain a compact with a high density ratio.
[0053]
The present inventor has established an epoch-making mold lubrication warm pressure molding method different from the conventional room temperature high pressure molding to solve this problem brilliantly. In this molding method, the filling step is a step of filling a raw material powder into a molding die in which a higher fatty acid-based lubricant is applied to the inner surface, and the molding step is a raw material powder filled in the molding die. Is a step of forming a metal soap film on the surface of the raw material powder in contact with the inner surface of the molding die by hot pressing.
[0054]
Next, this manufacturing method will be described in more detail.
(1) Filling process
In the filling process, it is necessary to apply a higher fatty acid lubricant to the inner surface of the molding die (application process).
This higher fatty acid-based lubricant may be a metal salt of a higher fatty acid in addition to the higher fatty acid itself. Examples of the higher fatty acid metal salts include lithium salts, calcium salts, and zinc salts. In particular, lithium stearate, calcium stearate, zinc stearate and the like are preferable. In addition, barium stearate, lithium palmitate, lithium oleate, calcium palmitate, calcium oleate, and the like can also be used.
[0055]
This coating step is preferably a step of spraying a higher fatty acid lubricant dispersed in water, an aqueous solution, an alcohol solution or the like in a heated molding die. When the higher fatty acid-based lubricant is dispersed in water or the like, the higher fatty acid-based lubricant is easily sprayed uniformly on the inner surface of the molding die. Further, when it is sprayed into the heated molding die, moisture and the like are quickly evaporated, and the higher fatty acid-based lubricant uniformly adheres to the inner surface of the molding die. The heating temperature of the molding die at that time needs to consider the temperature of the molding process described later, but it is sufficient to heat it to 100 ° C. or higher, for example. However, in order to form a uniform film of a higher fatty acid-based lubricant, it is preferable that the heating temperature be lower than the melting point of the higher fatty acid-based lubricant. For example, when lithium stearate is used as the higher fatty acid-based lubricant, the heating temperature is preferably less than 220 ° C.
[0056]
When the higher fatty acid-based lubricant is dispersed in water or the like, when the total weight of the aqueous solution is 100% by mass, the higher fatty acid-based lubricant is 0.1 to 5% by mass, When included in a proportion of 2% by mass, a uniform lubricating film is preferably formed on the inner surface of the molding die.
[0057]
Further, when the higher fatty acid-based lubricant is dispersed in water or the like, if the surfactant is added to the water, the higher fatty acid-based lubricant can be uniformly dispersed. Examples of such surfactants include alkylphenol surfactants, polyoxyethylene nonylphenyl ether (EO) 6, polyoxyethylene nonyl phenyl ether (EO) 10, anionic nonionic surfactants, and boric acid. Ester-based Emulbon T-80 or the like can be used. Two or more of these may be used in combination. For example, when lithium stearate is used as a higher fatty acid-based lubricant, three types of polyoxyethylene nonylphenyl ether (EO) 6, polyoxyethylene nonylphenyl ether (EO) 10 and borate ester Emulbon T-80 are available. It is preferable to use a surfactant at the same time. This is because the dispersibility of lithium stearate in water or the like is further activated when added in combination as compared with the case of adding only one of them.
[0058]
In order to obtain an aqueous solution of a higher fatty acid-based lubricant having a viscosity suitable for spraying, when the total amount of the aqueous solution is 100% by volume, the ratio of the surfactant is preferably 1.5 to 15% by volume.
[0059]
In addition, a small amount of an antifoaming agent (for example, a silicon-based antifoaming agent) may be added. This is because when the foaming of the aqueous solution is intense, it is difficult to form a uniform higher fatty acid lubricant film on the inner surface of the molding die when sprayed. The addition ratio of the antifoaming agent may be, for example, about 0.1 to 1% by volume when the total volume of the aqueous solution is 100% by volume.
[0060]
The higher fatty acid-based lubricant particles dispersed in water or the like preferably have a maximum particle size of less than 30 μm. When the maximum particle size is 30 μm or more, the higher fatty acid-based lubricant particles are likely to be precipitated in the aqueous solution, and it becomes difficult to uniformly apply the higher fatty acid-based lubricant to the inner surface of the molding die. Application of the aqueous solution in which the higher fatty acid-based lubricant is dispersed can be performed using, for example, a spray gun for painting, an electrostatic gun, or the like. In addition, as a result of investigating the relationship between the coating amount of the higher fatty acid-based lubricant and the extraction pressure of the powder molded body, the present inventor has found that the higher fatty acid-based lubricant has a film thickness of about 0.5 to 1.5 μm. It has been found preferable to apply a lubricant to the inner surface of the molding die.
[0061]
(2) Molding process
Although the details are not clear, it is considered that the above-described metal soap film is generated by a mechanochemical reaction in this step.
That is, by the reaction, the soft magnetic powder (or the coating when an insulating coating is formed on the particle surface) and the higher fatty acid-based lubricant are chemically bonded to each other to form a metal soap coating (for example, higher fatty acid iron). Salt film) is formed on the surface of the green compact. This metal soap film is firmly bonded to the surface of the powder molded body and exhibits a lubricating performance far superior to the higher fatty acid-based lubricant adhered to the inner surface of the molding die. As a result, the frictional force between the contact surfaces of the inner surface of the molding die and the outer surface of the powder molded body is remarkably reduced, and no galling or the like occurs despite high-pressure molding. And the powder compact was taken out from the molding die with a very low depressurization pressure, and the die life was not shortened. A typical example of the metal soap film is an iron stearate film or zinc stearate formed by the reaction of lithium stearate or zinc stearate, which is a higher fatty acid lubricant, with Fe.
[0062]
Since this metal soap film is formed even if each particle of the soft magnetic powder is coated with an insulating film, the necessary Fe is considered to be basically supplied from the insulating film. It is done. Of course, when the insulating coating originally contains a metal such as Fe, it is considered that Fe or the like appears in the insulating coating due to reaction or diffusion between the soft magnetic powder and the insulating coating.
[0063]
“Warm” in this molding step means that the molding step is performed under appropriate heating conditions according to each situation. However, in order to promote the reaction between the soft magnetic powder and the higher fatty acid-based lubricant, it is generally preferable that the molding temperature is 100 ° C. or higher. Moreover, in order to prevent the higher fatty acid-based lubricant from being altered, it is generally preferable that the molding temperature is 200 ° C. or lower. It is more preferable that the molding temperature is 120 to 180 ° C.
[0064]
The degree of “pressing” in the molding process is also appropriately determined according to the desired properties of the green compact, the composition of the raw material powder, the type of insulating coating or higher fatty acid lubricant, the material of the molding die, the internal properties, etc. It is to be decided. When this manufacturing method is used, molding can be performed under a high pressure that exceeds the conventional molding pressure. Therefore, even with a hard Fe-Si powder, a high-density compact can be easily obtained. . The molding pressure can be, for example, 700 MPa or more, 785 MPa or more, 1000 MPa or more, 1500 MPa or more, or even 2000 MPa or more. The higher the molding pressure, the higher the density of the green compact. However, it is preferable that the upper limit of the molding pressure be 2000 MPa in consideration of the life and productivity of the molding die.
[0065]
In addition, when this inventor pressure-molds pure Fe powder using this shaping | molding method, the extraction pressure becomes the maximum at a forming pressure of about 600 MPa, and it is rather experimentally that an extraction pressure falls rather than it. I have confirmed. And even when the molding pressure was changed in the range of 900 to 2000 MPa, the extraction pressure was a very low value of about 5 MPa. From this, it can be seen how excellent the lubricity of the metal soap film is. This forming method was actually very effective when high-pressure forming a hard Fe-Si powder. Such excellent moldability was the same even when higher fatty acid-based lubricants such as zinc stearate and calcium stearate were used in addition to lithium stearate.
[0066]
(3) Internal lubricant
When this mold lubrication warm pressure molding method is used, high pressure molding is possible without adding the conventionally required internal lubricant to the raw material powder. By adding no internal lubricant, it is possible to further increase the density and the magnetic flux density of the green compact.
[0067]
On the other hand, by adding the internal lubricant to the raw material powder, slip between the powder particles is improved, and galling between the molding die and the soft magnetic powder is prevented. Moreover, the internal lubricant also has an effect of suppressing plastic strain of the powder particles. Thereby, the coercive force of the green compact is reduced, and the hysteresis loss is also reduced.
[0068]
For example, the internal lubricant is preferably 0.1 to 0.6% by mass, and more preferably 0.2 to 0.5% by mass with respect to 100% by mass of the raw material powder coated with the insulating coating. If the amount is too small, the effect of the internal lubricant is not obtained. If the amount is too large, the density of the green compact cannot be increased and the magnetic properties are deteriorated.
[0069]
It is more preferable that the internal lubricant is the same lubricant as the higher fatty acid-based lubricant applied to the inner surface of the molding die. Specifically, zinc stearate or lithium stearate is preferable. The internal lubricant can be added to the raw material powder by various methods such as spraying, mixing, and dipping.
[0070]
Even when the internal lubricant is added (contained) to the raw material powder, there is no change in the above-described filling process and molding process. Further, when the powder compact obtained after the molding step is subjected to an annealing step or the like at a high temperature (for example, 650 ° C. or higher), the internal lubricant is decomposed and removed.
[0071]
(4) Heating process
The heating step is a step of heating and gradually cooling the powder molded body obtained after the molding step in order to remove residual stress and residual strain. As a result, a green compact with high saturation magnetization and excellent frequency response, low coercive force and small hysteresis loss can be obtained.
[0072]
The strain removed in this heating step may be strain accumulated in the soft magnetic powder particles before the molding step, plastic strain generated by plastic deformation during the molding step (molding strain), or both. However, when the soft magnetic powder is in a state in which residual stress or residual strain has been removed in advance by heat treatment or the like, this heating process mainly removes residual stress or residual strain applied to the soft magnetic powder by high pressure molding. The Rukoto.
[0073]
By the way, the heating temperature at this time is preferably set in a range in which the insulating coating is not destroyed in accordance with the heat resistance of the insulating coating. For example, when the insulating film is made of an oxide film having heat resistance, the annealing temperature may be 500 to 900 ° C., and further 600 to 800 ° C. As in the case of the raw material powder heating step, the heating atmosphere is preferably performed in an inert atmosphere. The heating time is 1 to 300 minutes, preferably 5 to 60 minutes, in view of the effect and economy.
[0074]
(4) Use of reactor
The reactor of the present invention may be used for any application, but is preferably used, for example, as a switching power source for industrial machines, household electric appliances, electric vehicles, hybrid vehicles, and the like. More specifically, for example, the reactor of the present invention is used in a voltage conversion circuit such as a DC-DC converter. The DC-DC converter is a high voltage (for example, 200 to 300V) DC power source for driving and a low voltage (for example, 12V) for auxiliary machines, like an electric vehicle and a hybrid vehicle that have recently been attracting attention. It is to convert to. In addition, in order to drive an induction machine, a reactor is also used for an inverter circuit or the like that converts a DC power source into an AC power source.
[0075]
The use frequency range of the reactor is preferably 1 to 50 kHz, 1 to 30 kHz, or even 5 to 20 kHz. By using this green compact, it is possible to reduce the size, performance, energy saving, noise, etc. of various devices.
[0076]
【Example】
Next, an Example is given and this invention is demonstrated more concretely.
(Example)
(1) Production of raw material powder
A gas water atomized powder having a composition of Fe-3% Si was prepared as a soft magnetic powder. The unit is mass% (hereinafter the same). N as the cooling gas during powder production₂Gas is used and the cooling rate is about 10^ThreeIt was estimated as ° C / sec. This was heat-treated at 950 ° C. for 3 hours in a hydrogen atmosphere. The properties of the soft magnetic powder thus obtained are as follows: average aspect ratio: 1.5, average number of crystal grains in one grain: 4, σ_10k: 1.98T, σ_r: 0.02T, iHc: 110 A / m. The magnetization σ_10kIs the magnetic flux density of the powder particles obtained in a magnetic field of 800 kA / m, σr is its residual magnetization, and iHc is its intrinsic coercivity.
[0077]
This soft magnetic powder was classified by sieving, and a powder having a weight average particle diameter of 30 to 70 μm was taken out and used. In addition, the weight average particle diameter was calculated | required from the particle size when integrating | accumulating from a fine particle (fine powder) and the weight reached to 50%.
[0078]
Each of the above powders was coated with an insulating film by the following method.
First, a coating treatment solution was prepared by dissolving a commercially available silicone resin (“SR-2400” manufactured by Toray Dow Corning Silicone Co., Ltd.) in 5 times the organic solvent (toluene). Next, this coating treatment liquid was sprayed into the raw material powder that was fluidized by an air flow, and then dried at 180 ° C. for 30 minutes. Thus, the surface of each powder particle was coated at a ratio of 1% by mass of the silicone resin with respect to 100% by mass of the soft magnetic powder (coating process) to obtain a raw material powder (coated powder) coated with the silicone resin.
[0079]
This silicone resin decomposes when heated at 400 ° C. or higher by the heat treatment described below, and the surface of the raw material powder is SiO.₂An oxide film (insulating film) is formed. This oxide film has an insulating property and maintains a high viscosity without being decomposed even at an annealing temperature described later. Thus SiO₂This oxide film is an insulating film having excellent heat resistance.
[0080]
(2) Manufacture of green compact
Using the obtained raw material powder, block-shaped compacts having the three shapes shown in Table 1 were produced by a mold lubrication warm press molding method. The specific manufacturing method is as follows. In addition, the compacting body which has 3 types of shapes shown in Table 1 is called the block 1, the block 2, and the block 3. The detailed cross-sectional shape of the block 3 is also shown in FIG.
[0081]
(1) Carbide molds having cavities corresponding to the respective block shapes shown in Table 1 were prepared. This molding die was preheated to 150 ° C. with a band heater. The inner peripheral surface of this molding die was previously subjected to TiN coating treatment, and the surface roughness was set to 0.4Z.
[0082]
1 cm of lithium stearate (higher fatty acid lubricant) dispersed in an aqueous solution is sprayed on the inner peripheral surface of the heated molding die with a spray gun.^ThreeThe coating was uniformly performed at a rate of about / sec (application process). The aqueous solution used here is obtained by adding a surfactant and an antifoaming agent to water. As the surfactant, polyoxyethylene nonylphenyl ether (EO) 6, (EO) 10 and boric acid ester Emulbon T-80 were used, and each was added by 1% by volume with respect to the entire aqueous solution (100% by volume). did. As the antifoaming agent, FS Antifoam 80 was used and 0.2% by volume was added to the entire aqueous solution (100% by volume).
[0083]
Further, lithium stearate having a melting point of about 225 ° C. and an average particle size of 20 μm was used. The dispersion amount is 100 cm of the aqueous solution.^ThreeTo 25 g. Then, this was further refined with a ball mill type pulverizer (Teflon-coated steel balls: 100 hours), and the obtained stock solution was diluted 20 times to give an aqueous solution having a final concentration of 1%, which was used in the coating step.
[0084]
{Circle around (2)} The above-mentioned various raw material powders that had been heated to 150 ° C., the same temperature as that, were naturally filled into the molding die coated with lithium stearate on the inner surface (filling step).
[0085]
(3) While filling the molding die at 150 ° C., each filled raw material powder was warm-pressure molded at a molding pressure of 1568 MPa (molding step).
[0086]
In this warm press molding, none of the raw material powders galling with the molding die, and the powder compact could be taken out from the die with a low pressure of about 5 MPa.
[0087]
(4) Non-oxygen atmosphere (N₂In a gas atmosphere or an Ar gas atmosphere), annealing (heat treatment) was performed appropriately (annealing temperature: 750 ° C., annealing time: 30 minutes) (heating process).
[0088]
(3) Manufacture of reactor cores
As shown in Table 2, the blocks 1 to 3 made of the obtained green compact are combined to produce the core 10 and the core 20 having the shapes shown in FIG. 2 (a), FIG. 2 (b) and FIG. did. FIG. 2 is a plan view thereof, and FIG. 3 is a perspective view of the core 10. As is apparent from FIG. 3, the core 10 has a two-stage configuration. The same applies to the core 20. Moreover, what was interposed between the opposing surfaces of each block is the resin board 5 which consists of PPS, and has the same cross-sectional shape as the blocks 1-3. However, as shown in Table 2, the thickness of the resin plate 5 is changed for each test piece. Thereby, the apparent magnetic permeability of the core 10 and the core 20 was adjusted. In addition, the blocks 1-3, the blocks 1-3, and the resin plate 5 were joined with an epoxy thermosetting resin.
[0089]
(Measurement)
A coated flat copper wire (6 × 1.5 mm) along the rated current was wound 46 to 60 turns around the core of each test piece shown in Table 2 to form a coil. The number of turns is determined from an inductance of 300 μH. An AC resistance value (AC resistance value at the time of mounting) was measured on this test piece using an LCR meter (manufacturer: HIOKI, model number: 3531Z) under conditions of 10 mA and 10 kHz. In addition, the alternating current resistance value (alternating current alternating current resistance value) when alternating current under the same conditions as above was passed through the coil alone was 200 mΩ.
[0090]
In addition, inverter evaluation was performed by connecting to an actual step-up switching power supply, and the weight characteristics and loss (current value: 20 A) of the reactor were evaluated. These results are also shown in Table 2.
[0091]
The measurement of the magnetic properties was performed by preparing a ring-shaped test piece (outer diameter: φ39 mm × inner diameter φ30 mm × thickness 5 mm) made of the above-described compacted body. The static magnetic field characteristics were measured with a direct current magnetic flux meter (manufacturer: Toei Kogyo, model number: MODEL-TRF). The iron loss is measured by a BH analyzer (manufacturer: Iwasaki Tsushinki Co., Ltd., model number: SY-8232) with each core placed in a 10 kHz, 0.2 T magnetic field. I used what was wound around. This iron loss is the sum of hysteresis loss and eddy current loss. The magnetic flux density in the static magnetic field indicates the magnetic flux density generated in 10 kA / m._10kAs shown. The saturation magnetization (Ms) shown in the table is the value of the magnetic flux density (B) at 0.1 MA / m. The density (ρ) of the green compact was measured by the Archimedes method. The true density of Fe-3% Si (ρ₀) Is 7.67x10^Threekg / m^ThreeIt is. Based on this, the density ratio (ρ / ρ₀) And the results are also shown in Table 2.
[0092]
(Evaluation)
As shown in Table 2, the reactor of the present invention has excellent direct current superposition characteristics and a small loss. Specimen No. 4 having a thickness of resin plate 5 exceeding 4 mm was used. In No. 5, although the iron loss of the ring test piece was the same as that of the other test pieces, the loss of the actual reactor tripled the loss due to the leakage magnetic flux.
[0093]
Attached AC resistance value r shown in Table 2₁ 4 is a bar graph. As is apparent from the graph of FIG. The AC resistance values of 1 to 4 are much lower than those of other test pieces. It is thought that the decrease in the AC resistance value at the time of wearing leads to the decrease in the copper loss. In addition, the test piece with less copper loss has an AC resistance value that is 2.5 times or less than the AC resistance value of the coil alone (AC resistance value when the coil is single), as shown in Table 2 and FIG. It is clear from the graph of FIG.
[0094]
[Table 1]

[0095]
[Table 2]

[Brief description of the drawings]
FIG. 1 is a view showing a cross-sectional shape of one compacting body constituting a reactor core.
FIG. 2 is a plan view showing one embodiment of a reactor core according to the present invention, in which FIG. 2 (a) is a combination of cuboid compacts, and FIG. 2 (b) is a cuboid. A green compact and a U-shaped green compact are combined.
FIG. 3 is a perspective view of the reactor core shown in FIG.
FIG. 4 is a bar graph showing an AC resistance value for each test piece.
[Explanation of symbols]
1-3 blocks
5 Resin plate
10 cores
20 cores

Claims (8)

Reactor comprising a combination of at least two compacted compacts made of a soft magnetic powder containing iron (Fe) as a main component and compression-molding a raw powder whose particle surface is covered with an insulating coating. Core for,
A reactor comprising a coil wound around a conducting wire and attached to the reactor core,
The green compact has a density ratio (ρ / ρ ₀ :%) that is a ratio of the bulk density (ρ) to the true density (ρ ₀ ) of the soft magnetic powder is 90% or more,
The core for reactor has a non-magnetic material having a width of 4 mm or less different from the insulating coating at one or more positions between opposed surfaces where each of the combined powder compacts is abutted.
The reactor core saturation magnetization is 1.7 T or more,
The first apparent permeability (μ _5k ) obtained when a magnetic field of 5 kA / m is applied to the reactor core is 25 or more, and the second apparent permeability obtained when a magnetic field of 35 kA / m is applied ( mu _35k) has a first saw KakeToru permeability (μ _5k) 70% or more,
An AC resistance value (r ₁ ) at the time of installation, which is an AC resistance value of the coil obtained when 10 kHz of alternating current of 10 kHz flows through the coil in a state of being mounted on the reactor core, is mounted on the reactor core. Less than 2.5 times (r ₁ ≦ 2.5r ₀ ) of the single-unit AC resistance value (r ₀ ), which is the AC resistance value of the coil obtained when 10 mA of AC current flows through the coil alone in a state of 10 kHz. A reactor characterized by being. The reactor according to claim 1, wherein the AC resistance value when mounted is 1Ω or less. The reactor according to claim 1 , wherein the nonmagnetic material is a resin material . A reactor core comprising a combination of at least two compacted compacts made of a soft magnetic powder comprising Fe as a main component and compression-molding a raw powder whose particle surface is coated with an insulating coating ; ,
A reactor comprising a coil wound around a conducting wire and attached to the reactor core,
The green compact has a density ratio (ρ / ρ ₀ :%) that is a ratio of the bulk density (ρ) to the true density (ρ ₀ ) of the soft magnetic powder is 90% or more,
The reactor core is combined with a non-magnetic material having a width of 4 mm or less different from the insulating coating at one or more positions between the opposing surfaces of the compacting body constituting a magnetic path in combination.
The reactor is a reactor in which a rectangular copper wire is wound for 30 turns or more. A reactor core comprising a combination of at least two compacted compacts made of a soft magnetic powder comprising Fe as a main component and compression-molding a raw powder whose particle surface is coated with an insulating coating. There,
The green compact has a density ratio (ρ / ρ ₀ :%) that is a ratio of the bulk density (ρ) to the true density (ρ ₀ ) of the soft magnetic powder is 90% or more,
The reactor core is formed by interposing a non-magnetic material having a width of 4 mm or less, which is different from the insulating coating, at one or more positions between opposing surfaces of the compacting body that are combined to form a magnetic path. Reactor core. A reactor core comprising a combination of at least two compacted compacts of a raw material powder comprising a soft magnetic powder containing Fe as a main component and the surface of the soft magnetic powder coated with an insulating coating . A manufacturing method comprising:
The green compact includes a filling step of filling the raw material powder into a molding die in which a higher fatty acid-based lubricant is applied on the inner surface, and heating the raw material powder filled in the molding die. It produced a metallic soap coating so produced by the molding step of obtaining the green compact to pressure molding to the surface of the soft magnetic powder in contact with the inner surface of the molding mold between the true density of the soft magnetic powder ([rho ₀₎ density ratio is the ratio of the bulk density ([rho) against (ρ / ρ _0:%) is Ri der 90%
A plurality of compacted compacts obtained by interposing a non-magnetic material different from the insulating coating having a width of 4 mm or less at one or more positions between opposing surfaces formed when the obtained compacted compacts are brought into contact with each other. A method for manufacturing a reactor core, wherein the reactor core is combined . The said compacting body is a manufacturing method of the core for reactors of Claim 6 obtained through the heating process which further heats the compacting body obtained after the said shaping | molding process, and removes a residual stress or a residual distortion. . The method for manufacturing a reactor core according to claim 6, wherein the soft magnetic powder is an Fe—Si powder containing 2 to 5 mass% of silicon (Si), and an insulating film is formed on the surface thereof.

Images