JP5831941B2 - Manufacturing method of outer core - Google Patents

Description

  The present invention is manufactured by a manufacturing method of an outer core that manufactures an outer core that is exposed from the coil and constitutes a part of the reactor, and is manufactured by the manufacturing method. The present invention relates to an outer core and a reactor including the outer core. In particular, the present invention relates to a method of manufacturing an outer core effective for reducing reactor loss.

  A hybrid vehicle or the like includes a booster circuit in a power supply system to a motor. A reactor is used as one component of this booster circuit. As this reactor, there exists a thing shown in patent document 1, for example.

  As shown in FIG. 7, the reactor of Patent Document 1 includes a coil 105, an inner core 101 c disposed in the coil 105, and an outer core 101 e disposed exposed from the coil 105. More specifically, as shown in FIG. 8, the coil 105 is formed by connecting a pair of coil elements 105a and 105b, in which a winding 105w is spirally wound, in a parallel state. The inner core 101c is a columnar body having a rectangular cross section, and is disposed inside each of the coil elements 105a and 105b. The outer core 101e is a columnar body that is exposed from the coil 105 and has a substantially trapezoidal (trapezoidal) upper and lower surface, and forms an annular core facing the end surfaces of both inner cores 101c. These constituent members are combined together from the left-right direction in FIG. 8 to form the reactor 100 shown in FIG.

  The outer core 101e is formed by using, as a raw material powder, a coated soft magnetic powder comprising a plurality of coated soft magnetic particles obtained by coating soft magnetic particles with an insulating coating, and pressing the raw material powder. The pressurization is generally performed by filling a molding space formed by a relatively movable columnar first punch and a cylindrical die with a coated soft magnetic powder, Is performed by compressing the coated soft magnetic powder in the molding space. At that time, the coated soft magnetic powder is compressed so that the first punch and the second punch form the upper and lower surfaces of the outer core. This is because the compacting of the green compact is generally performed by compressing the raw material powder so that the cross section of the compact having a cut surface in the direction orthogonal to the pressing direction is uniform.

JP 2010-272772 A

  The outer core manufactured as described above has an outer surface surrounded by the die, that is, a surface parallel to the direction to be pressed (a surface perpendicular to the magnetic flux direction). There is a possibility that the insulating coating of the coated soft magnetic particles may be damaged by sliding contact with the mold when the body is removed. When the insulating coating is damaged, the soft magnetic particles may be exposed and spread, and as a result, the soft magnetic particles in the compacted body are electrically connected to each other to form a substantially film-like conductive part, resulting in an eddy current. There is a possibility that the loss increases and the magnetic properties of the outer core deteriorate.

  The present invention has been made in view of the above circumstances, and one of its purposes is to provide an outer core manufacturing method capable of manufacturing an outer core effective in reducing reactor loss.

  Another object of the present invention is to provide an outer core manufactured by the manufacturing method of the present invention.

  Another object of the present invention is to provide a low-loss reactor.

  The present invention achieves the above-mentioned object by specifying the pressing direction, that is, pressing a specific surface of the green compact when the outer core is pressed. Specifically, the coated soft magnetic powder is compressed in a direction in which the cross section of the molded body having a cut surface in a direction orthogonal to the pressing direction is non-uniform.

  The manufacturing method of the outer core of the present invention is a method of manufacturing an outer core included in the following reactor by pressure molding. The reactor includes a coil, an inner core, and an outer core. More specifically, the coil is formed by connecting a pair of coil elements in which windings are spirally wound in parallel with each other. There is a pair of inner cores, which are arranged inside each of the coil elements. A pair of the outer cores are exposed from the coil and are connected to the inner cores to form the inner core and the annular core. In addition, it includes a connection surface with the inner core and an opposing surface facing the other outer core with the inner core interposed therebetween. And when the said outer core is planarly viewed from the axial direction of the said annular core, as for the planar shape of the said outer core, the opposite side is the said opposing side rather than the opposing side with the said inner core. The shape in the width direction along the surface is small. The manufacturing method is a manufacturing method for manufacturing the outer core, and includes a preparation step and a molding step. In the preparation step, a coated soft magnetic powder comprising a plurality of coated soft magnetic particles in which a soft magnetic particle is coated with an insulating coating is prepared as a raw material powder for the outer core. In the molding process, the coating soft magnetic powder is filled in a molding space formed by a relatively movable columnar first punch and a cylindrical die, and is arranged opposite to the first punch and the first punch. The coated soft magnetic powder in the molding space is pressure-molded by a columnar second punch. In that case, the said opposing surface in the said outer core is pressurized with the said 2nd punch.

  According to the manufacturing method of the present invention, an outer core that is effective in reducing reactor loss can be manufactured. In the molding step, by pressing the surface to be the facing surface, the surface does not slide in contact with the mold during pressurization or demolding. For this reason, the insulating coating of the coated soft magnetic powder on the facing surface is hardly damaged, and it is difficult to form a conducting portion where the soft magnetic particles are conducted. The facing surface includes a connecting surface connected to the inner core, and when the reactor is assembled and the coil is excited, the connecting surface becomes a linkage surface through which the magnetic flux passes substantially orthogonally. That is, since it is difficult for the conductive portion to be formed on the facing surface, eddy current is hardly generated on the surface of the coupling surface, and eddy current loss can be reduced.

  One aspect of the production method of the present invention is that the soft magnetic particles are pure iron.

  According to the above method, even if the soft magnetic particles are pure iron, it is possible to produce an outer core that is effective in reducing the reactor loss. Since pure iron is soft, it is easily deformed when pressure-molded, and the insulating coating is easily damaged by sliding contact with the mold when the coated soft magnetic powder is pressed or when the molded body is removed. Therefore, the conductive part is easily formed and loss is likely to increase. However, by pressurizing the surface to be the facing surface, it is difficult to form a conduction part on the facing surface, and therefore, an eddy current hardly occurs on the surface of the facing surface. As a result, even if the soft magnetic particles are pure iron, an outer core that can reduce the loss can be manufactured.

As one form of the manufacturing method of this invention, it is mentioned that the planar shape of the said outer core is either of following (A)-(C).
(A) A bow shape in which the opposite side of the outer core to the inner core is a string and the opposite side is an arc.
(B) A trapezoidal shape with the long side of the outer core facing the inner core.
(C) U-shape in which the opposite side of the outer core to the inner core is an opening.

  According to said method, even if the planar shape of an outer core is any of the above, the outer core effective in reducing the loss of a reactor can be manufactured. The above-mentioned bow shape includes a substantially bow shape having a string and an arc in addition to an arc shape formed only by a string and an arc. Specifically, a shape in which a part of the arc is cut out in parallel with the string, a shape having a protruding portion that protrudes in the opposite direction from a part of the arc, and the like can be given. The same applies to the trapezoidal shape and U-shape. That is, the trapezoidal shape includes a substantially trapezoid having a long side and a short side, in addition to a trapezoid formed by a long side and a short side opposite to the long side. Specifically, the shape which has the protrusion part which protrudes in the short side of a trapezoid is mentioned. The U-shape includes a substantially U-shape having an opening in addition to the U-shape having an opening on the opposite side. Specifically, it includes a shape in which a part on the opposite side of the opening is cut out in parallel with the connecting surface, and a shape having a protruding part that protrudes in the opposite direction from a part on the opposite side. Each of the protrusions may have a uniform shape in the opposite direction, or may have a shape in which the width decreases from the opposite side toward the opposite direction. For example, in addition to a polygonal shape such as a rectangle, a bow shape, a semicircular shape, and the like can be given.

As one form of the production method of the present invention, the planar shape of the outer core may further include at least one of the following (D) and (E).
(D) An opposing surface-side rectangular surface having a long side parallel to the pressing surface of the second punch in the opposing surface.
(E) A rectangular surface opposite to the opposing surface, the longer side being a surface parallel to the opposing surface.

  According to said method, when manufacturing the outer core which provides the said opposing surface side rectangular surface, at the time of pressurization, the press surface of a 2nd punch in the internal peripheral surface of die | dye, and a surface non-orthogonal and 2nd punch Since a distance corresponding to the thickness of the opposing rectangular surface to be formed is formed between them, the non-orthogonal surface and the second punch can be prevented from colliding with each other, and the die and the second punch can be damaged. Can be prevented. In addition, compared to the case where the opposed surface side rectangular surface is not provided, a sufficient pressure can be applied to the coated soft magnetic powder, and a high-density outer core can be easily manufactured. Furthermore, it is possible to prevent formation of sharp corners that are easily chipped at both ends in the width direction of the opposing surface of the outer core.

  On the other hand, when an outer core having the opposite rectangular surface is manufactured, a distance corresponding to the thickness of the opposite rectangular surface to be formed is formed between the first punch and the die during pressing. Therefore, it is possible to prevent the first punch from entering the die inner side (second punch side) relative to the predetermined position. Therefore, when the first punch enters the inside of the die (second punch side), it is possible to prevent formation of sharp corners that are easily chipped at both ends in the width direction on the opposite side of the facing surface of the outer core.

  As one form of the manufacturing method of this invention, when providing the said opposing surface side rectangular surface at least, the thickness of the said opposing surface side rectangular surface is 0.3 mm or more and 2.0 mm or less.

  According to said method, if it manufactures so that the thickness of the opposing surface side rectangular-shaped surface may be 0.3 mm or more, the surface which is not orthogonal to the pressurization surface of the 2nd punch in the internal peripheral surface of die | dye at the time of pressurization And the second punch can be sufficiently prevented from colliding with each other. On the other hand, by manufacturing so that the thickness of the opposing surface side rectangular surface is 2.0 mm or less, the coated soft magnetic material on the opposing surface side disposed near the coil when the reactor is constructed during pressurization or demolding The area where the powder and the die are in sliding contact can be reduced. Therefore, damage to the insulating coating can be suppressed and eddy current loss can be reduced.

  As one form of the manufacturing method of the present invention, when at least the opposite rectangular surface is provided, when the thickness from the opposing surface of the outer core to the opposite surface of the opposing surface is t, the opposite rectangular surface The shape surface has a thickness of 0.5 mm or more and t / 2 or less.

  According to the above method, if the opposite rectangular surface is manufactured to have a thickness of 0.5 mm or more, the first punch relatively enters the inside of the die (second punch side) during pressurization. It can be prevented sufficiently. On the other hand, by setting the thickness of the opposite rectangular surface to t / 2 or less, the opposite rectangular surface with respect to the entire outer core does not increase too much.

  As one form of the manufacturing method of this invention, when the planar shape of the said outer core comprises both the said opposing surface side rectangular surface and the said opposite side rectangular surface, the thickness of the said opposing surface side rectangular surface is The thickness is smaller than the thickness of the opposite rectangular surface.

  According to the above configuration, by reducing the thickness of the opposing surface side rectangular surface, the sliding contact area with the die can be reduced, and the generation of eddy currents generated in the circumferential direction of the opposing surface side rectangular surface can be suppressed. Therefore, the outer core effective for reducing the loss of the reactor can be manufactured.

  The outer core of the present invention is manufactured by the method for manufacturing the outer core of the present invention.

  According to the outer core of the present invention, since eddy currents hardly occur on the surface of the facing surface, it can be suitably used for a reactor. This is because according to the outer core of the present invention, when the reactor is assembled, at least a part of the facing surface where the conducting portion is not formed is connected to the end surface of the inner core, so that a vortex is formed on the surface of the facing surface. This is because current is difficult to generate, which is effective in reducing reactor loss.

  The reactor of the present invention includes a coil, an inner core, and an outer core. The coil is formed by connecting a pair of coil elements in which windings are spirally wound in parallel to each other. The inner core is disposed inside the coil elements. The outer core is exposed from the coil and has a facing surface facing a side facing the inner core to form an annular core with the inner core. The outer core is the outer core of the present invention.

  According to the reactor of the present invention, it is possible to achieve a low loss by providing the outer core on which the eddy current hardly occurs on the facing surface facing the side facing the inner core.

  The outer core manufacturing method of the present invention can manufacture an outer core that is effective in reducing reactor loss.

  The outer core of the present invention can construct a low-loss reactor.

  The reactor of the present invention can have a low loss.

FIG. 6 is a process explanatory diagram illustrating an example of a procedure in the outer core manufacturing method according to the first embodiment. It is process explanatory drawing which shows the outline of an example of the procedure in the manufacturing method of the outer core which concerns on the modification 1. FIG. It is process explanatory drawing which shows the outline of an example of the procedure in the manufacturing method of the outer core which concerns on the modification 2. It is process explanatory drawing which shows the outline of an example of the procedure in the manufacturing method of the outer core which concerns on the modification 3. It is process explanatory drawing which shows the outline of an example of the procedure in the manufacturing method of the outer core which concerns on the modification 4. It is process explanatory drawing which shows the outline of an example of the procedure in the manufacturing method of the outer core which concerns on the modification 5. It is a perspective view which shows the outline of the reactor which concerns on Embodiment 2. FIG. It is a disassembled perspective view which shows the outline of each structure of the reactor which concerns on Embodiment 2. FIG.

  Embodiments of the present invention will be described below. First, an outer core manufacturing method capable of manufacturing an outer core effective for reducing reactor loss will be described, and then an example of a reactor including the outer core will be described.

Embodiment 1
[Method of manufacturing outer core]
The outer core manufacturing method of the present invention is a method of manufacturing an outer core included in a reactor by pressure molding. As will be described later in detail, the reactor includes a coil 105, an inner core 101c, and an outer core 101e as shown in FIG. Specifically, the coil 105 is formed by connecting a pair of coil elements 105a and 105b, in which a winding 105w is spirally wound, in parallel with each other. The inner core 101c is arranged inside the coil elements 105a and 105b. The outer core 101e is exposed from the coil 105 and connected to each inner core 101c to form the inner core 101c and the annular core 101. In addition, it includes a connection surface with the inner core 101c and an opposing surface that faces the other outer core 101e. Each of the connection surfaces is a flat surface and is disposed flush with each other. Moreover, the opposing surface containing both connection surfaces is also a plane. When the outer core 101e is viewed in plan from the axial direction of the annular core 101, the planar shape of the outer core 101e is opposite to the opposite side of the outer core 101e opposite to the inner core 101c. The shape in the width direction along the surface is small. A specific manufacturing method of the outer core 101e includes a preparation process and a molding process. Hereafter, after explaining the molding die used for manufacture, each process is explained in order.

[Mold for molding]
The mold used in the manufacturing method of the present invention typically has a cylindrical die provided with a through hole, and a pair of columnar first punches that can be inserted from the openings of the through hole of the die. And a second punch. The pair of first punch and second punch are arranged to face each other in the through hole. In this mold, a bottomed cylindrical molding space is formed by one surface of one punch (the pressure contact surface facing the other punch) and the inner peripheral surface of the die. The molding powder is filled with raw material powder, which will be described later, and pressed and compressed with both punches to produce an outer core. Each opposing surface of both punches forms each end surface of the outer core, and the inner peripheral surface of the die forms the outer peripheral surface of the outer core.

  More specifically, the molding die 1 includes, for example, a cylindrical die 10A having a through hole 10b as shown in FIG. 1, and a pair of columnar upper punch 11 and lower punch inserted into and removed from the through hole 10b. The thing which comprises 12 is mentioned. In FIG. 1, the die 10 </ b> A and the lower punch 12 show a longitudinal section.

(Die)
The longitudinal sectional shape of the inner periphery of the through hole provided in the die may be a shape corresponding to the shape of the outer core in plan view. For example, it is only necessary that the other punch side of the die has an inner peripheral shape in which the dimension in the width direction of the die is smaller than the one punch side. In addition, the inner peripheral shape is not particularly limited as long as it can press the surface of the outer core facing the inner core with one punch. Specifically, the through-hole provided in the die includes a large rectangular hole through which one punch is inserted, a small rectangular hole through which the other punch is inserted, and a large rectangular hole to a small rectangular hole between both rectangular holes. The dimension of the width direction becomes small, and it is comprised by the taper hole which neither punch is penetrated. That is, the inner peripheral surface of the large rectangular hole is a parallel region parallel to the side surface of one punch, the inner peripheral surface of the small rectangular hole is a parallel region parallel to the side surface of the other punch, and the inner peripheral surface of the tapered hole. Is a non-parallel region that is not parallel to the side surface of any punch.

  More specifically, as shown in FIG. 1A, a large rectangular hole 10p (opposing surface side parallel region) through which the upper punch 11 is inserted into the upper punch 11 side of the die 10A and a lower punch 12 side. Between the small rectangular hole 10r (opposite side parallel region) through which the punch 12 is inserted and the upper surface 10u (upper punch 11) side of the die 10A between the rectangular holes, the lower side (lower punch 12) side of the die 10A is more. An inner peripheral shape constituted by a taper hole 10c (non-parallel region) in which the dimension of the die 10A in the width direction (the left-right direction in the drawing) is reduced. Here, the inner peripheral shape of the tapered hole 10c is that the upper surface 10u side, that is, the lower end of the large rectangular hole 10p is a chord, the lower punch 12 side, that is, the upper end side of the small rectangular hole 10r is an arc, and a part of the arc is formed. A substantially arcuate shape (bow shape) parallel to the string. Here, the lower end of the large rectangular hole 10p refers to the boundary between the large rectangular hole 10p and the tapered hole 10c, and the upper end of the small rectangular hole 10r refers to the boundary between the small rectangular hole 10r and the tapered hole 10c. The thickness of the through hole 10b of the die 10A (the vertical direction in the drawing) is uniform in the depth direction of the through hole 10b (the vertical direction on the drawing). That is, the cross-sectional shape of both rectangular holes 10p and 10r is uniform in the direction in which both punches 11 and 12 face each other, and the cross-sectional shape of the tapered hole 10c decreases from the large rectangular hole 10p side to the small rectangular hole 10r side. ing.

(Upper punch and lower punch)
The upper punch 11 and the lower punch 12 are columnar bodies that can be inserted into the through holes of the die. A lower surface 11d of the upper punch 11 that faces the lower punch 12 has a shape suitable for the space created by the die 10A. The shape of the lower surface 11d of the upper punch 11 forms the shape of the surface facing the inner core in the outer core. Here, the lower surface 11d of the upper punch 11 is a rectangular plane, and the upper punch 11 is wider than the lower punch 12 (the distance in the left-right direction in FIG. 1). A surface corresponding to the upper punch 11 of the molded body press-formed by the upper punch 11 is a rectangular plane. Each of the upper punch 11 and the lower punch 12 is an integrally molded product of a quadrangular prism member.

  The pressure contact surface of the upper punch 11 forms a facing surface of the outer core, and the pressure contact surface of the lower punch 12 forms an end surface opposite to the facing surface of the outer core.

  Examples of the constituent material of the molding die 1 include an appropriate high-strength material (such as high-speed steel) that has been conventionally used for molding a green compact (mainly composed of metal powder).

(Movement mechanism)
At least one of the pair of punches and the die are relatively movable. In the molding die 1 shown in FIG. 1, the lower punch 12 is fixed to a main body device (not shown) and does not move, and the die 10 </ b> A and the upper punch 11 can be moved in the vertical direction by a moving mechanism (not shown). In addition, the die 10A can be fixed and the punches 11 and 12 can be moved, and the die 10A and the punches 11 and 12 can be moved. By fixing one punch (here, the lower punch 12), the moving mechanism is not complicated, and the moving operation can be easily controlled.

  If the die is configured to be relatively movable, the green compact can be easily removed.

<Others>
In the production method of the present invention, a lubricant can be applied to a molding die (in particular, the inner peripheral surface of the die). Lubricant is a metal soap such as lithium stearate, a fatty acid amide such as stearic acid amide, a solid lubricant such as higher fatty acid amide such as ethylenebisstearic acid amide, a solid lubricant dispersed in a liquid medium such as water. Examples thereof include liquids and liquid lubricants. However, the smaller the amount of lubricant used (applied thickness), the higher the proportion of the magnetic component is obtained.

  Here, as shown in FIG. 1, the upper punch 11 and the lower punch 12 are shown as integrally formed, but at least one of the upper punch and the lower punch is composed of a plurality of members. Also good. In that case, it can also be set as the structure which each member can each move independently.

[Preparation process]
In the preparation step, a coated soft magnetic powder that is a raw material powder for the outer core is prepared. The coated soft magnetic powder includes a plurality of coated soft magnetic particles in which an insulating coating is coated on the outer periphery of the soft magnetic particles.

{Soft magnetic particles}
(composition)
The soft magnetic particles preferably contain 50 mass% or more of iron, and are iron alloys such as Fe-Si alloys, Fe-Al alloys, Fe-N alloys, Fe-Ni alloys, Fe-C alloys. An alloy, an Fe-B alloy, an Fe-Co alloy, an Fe-P alloy, an Fe-Ni-Co alloy, and an Fe-Al-Si alloy can be used. Then, eddy current loss can be easily reduced and the loss can be further reduced. In particular, from the viewpoint of magnetic permeability and magnetic flux density, pure iron in which 99% by mass or more is Fe is preferable.

(Particle size)
The average particle diameter of the soft magnetic particles may be any size that contributes to low loss as a green compact. That is, although it can select suitably, without specifically limiting, For example, if it is 1 micrometer or more and 150 micrometers or less, it is preferable. By setting the average particle size of soft magnetic particles to 1 μm or more, the increase in coercive force and hysteresis loss of compacts made using soft magnetic powder is suppressed without reducing the fluidity of soft magnetic powder. it can. Conversely, by setting the average particle size of the soft magnetic particles to 150 μm or less, eddy current loss that occurs in a high frequency region of 1 kHz or more can be effectively reduced. The average particle size of the soft magnetic particles is more preferably 40 μm or more and 100 μm or less. If the lower limit of the average particle diameter is 40 μm or more, an effect of reducing eddy current loss can be obtained, and handling of the coated soft magnetic powder becomes easy, and a molded body having a higher density can be obtained. The average particle diameter means a particle diameter of particles in which the sum of masses from particles having a small particle diameter reaches 50% of the total mass in the particle diameter histogram, that is, 50% particle diameter.

(shape)
The shape of the soft magnetic particles is preferably such that the aspect ratio is 1.2 to 1.8. The aspect ratio is the ratio between the maximum diameter and the minimum diameter of the particles. Soft magnetic particles having an aspect ratio in the above range can increase the demagnetizing factor when formed into a compact, compared to those having a small aspect ratio (close to 1.0), and have excellent magnetic properties. It can be set as a molded body. In addition, the strength of the green compact can be improved.

(Manufacturing method)
The soft magnetic particles are preferably produced by an atomizing method such as a water atomizing method or a gas atomizing method. Since the soft magnetic particles produced by the water atomization method have many irregularities on the particle surface, it is easy to obtain a high-strength molded product by meshing the irregularities. On the other hand, the soft magnetic particles produced by the gas atomization method are preferable because the particle shape is almost spherical, and there are few irregularities that break through the insulating coating. A natural oxide film may be formed on the surface of the soft magnetic particles.

{Insulation coating}
The insulating coating is covered with soft magnetic particles in order to insulate adjacent soft magnetic particles. By covering the soft magnetic particles with an insulating coating, the contact between the soft magnetic particles can be suppressed, and the relative magnetic permeability of the compact can be suppressed. In addition, the presence of the insulating coating can suppress the eddy current from flowing between the soft magnetic particles, thereby reducing the eddy current loss of the green compact.

(composition)
The insulating coating is not particularly limited as long as it has excellent insulating properties that can ensure insulation between soft magnetic particles. For example, examples of the material for the insulating film include phosphate, titanate, silicone resin, and two layers of phosphate and silicone resin.

  In particular, since the insulating coating made of phosphate is excellent in deformability, even when soft magnetic particles are deformed when a soft magnetic material is pressed to produce a compact, a deformation follows the deformation. Can do. Further, the phosphate coating has high adhesion to iron-based soft magnetic particles and is difficult to fall off from the surface of the soft magnetic particles. As the phosphate, a metal phosphate compound such as iron phosphate, manganese phosphate, zinc phosphate, or calcium phosphate can be used.

  In the case of an insulating coating made of a silicone resin, it is excellent in heat resistance, so that it is difficult to be decomposed in a heat treatment step to be described later, and the insulation between soft magnetic particles can be maintained well until the compacting body is completed.

  When the insulating coating has a two-layer structure of the phosphate and the silicone resin, it is preferable to coat the phosphate on the soft magnetic particle side and the silicone resin directly on the phosphate. Since the silicone resin is coated directly on the phosphate, it is possible to have the characteristics of both the phosphate and the silicone resin described above.

(Film thickness)
The average thickness of the insulating coating may be a thickness that can insulate adjacent soft magnetic particles. For example, it is preferably 10 nm or more and 1 μm or less. By setting the thickness of the insulating coating to 10 nm or more, it is possible to effectively suppress contact between soft magnetic particles and energy loss due to eddy current. On the other hand, by setting the thickness of the insulating coating to 1 μm or less, the ratio of the insulating coating to the coated soft magnetic particles does not become too large, and the magnetic flux density of the coated soft magnetic particles can be prevented from significantly decreasing.

  The thickness of the insulating coating can be examined as follows. First, the film composition obtained by composition analysis (TEM-EDX: transmission electron microscopic energy dispersive X-ray spectroscopy), and the amount of inductively coupled plasma mass (ICP-MS) obtained by inductively coupled plasma Considering this, a considerable thickness is derived. Then, the film is directly observed with a TEM photograph, and the average thickness determined by confirming that the order of the equivalent thickness derived earlier is an appropriate value is used.

(Coating method)
The method for coating the soft magnetic particles with the insulating coating may be appropriately selected. For example, the film may be formed by hydrolysis / polycondensation reaction. Soft magnetic particles and a material constituting the insulating coating are blended, and the blend is mixed in a heated state. By doing so, the soft magnetic particles can be sufficiently dispersed in the coating material, and the insulating coating can be coated on the outside of the individual soft magnetic particles.

  The heating temperature and mixing time may be appropriately selected. By selecting the heating temperature and the rotational speed of the mixer, the soft magnetic particles can be more sufficiently dispersed, and it becomes easy to coat the individual particles with the insulating coating.

[Molding process]
In the molding step, the coated soft magnetic powder is pressure-molded using the molding die 1 described above. In this step, a coating space 31 made of the lower punch 12 and the cylindrical die 10A in the mold 1 is filled with the coated soft magnetic powder, which is the raw material powder P of the outer core, and the upper punch 11, the lower punch 12, Thus, the coated soft magnetic powder in the molding space 31 is pressure-molded.

{Molding procedure}
(Filling process)
First, as shown in FIG. 1A, the upper punch 11 is moved to a predetermined standby position above the through hole 10b in the die 10A. Further, the die 10A is moved upward, and a predetermined molding space 31 is formed by the upper surface 12u of the lower punch 12 and the through hole 10b of the die 10A. At that time, in the next pressurizing step, the lower punch 12 may be arranged in consideration of the distance by which the die 10A descends when pressurizing. Here, the upper surface 12u of the lower punch 12 is positioned in the small rectangular hole 10r of the die 10A so as to be positioned on the lower opening side of the die 10A from the upper end of the small rectangular hole 10r by an amount corresponding to the downward movement of the die 10A during pressurization. The lower punch 12 is disposed.

  The above-mentioned coated soft magnetic powder is prepared as a raw material powder. Then, as shown in FIG. 1 (B), the prepared raw material powder P is filled into a forming space 31 formed by the die 10A and the lower punch 12 by a powder feeding device (not shown).

(Pressure process)
As shown in FIG. 1C, the upper punch 11 is moved downward and inserted into the large rectangular hole 10p of the through hole 10b of the die 10A, and the raw powder P is pressurized and compressed by both punches 11 and 12. To do.

  Although the pressure to pressurize can be selected suitably, for example, if the compacting body used as the core for reactors is manufactured, it is preferred to set it as about 490-1470 MPa, especially about 588-1079 MPa. By setting it to 490 MPa or more, the raw material powder P can be sufficiently compressed, the relative density of the outer core can be increased, and by setting it to 1470 MPa or less, damage to the insulating coating due to contact between the coated soft magnetic particles constituting the raw material powder P Can be suppressed.

  The die 10A is lowered during pressurization, and when the pressurization is completed, the position of the upper surface 12u of the lower punch 12 is positioned at the upper end of the small rectangular hole 10r of the die 10A.

(Removal process)
After performing the predetermined pressurization, the die 10A is moved relative to the molded body 41 as shown in FIG. Here, the molded body 41 is not moved, and only the die 10A is moved downward. At this time, a contact area with the die 10A in the outer peripheral surface of the molded body 41 is in sliding contact with the through hole 10b of the die 10A by a reaction force from the die 10A.

  The die 10A is moved until the upper surface 10u of the die 10A and the upper surface 12u of the lower punch 12 are flush with each other, or until the upper surface 12u of the lower punch 12 is positioned above the upper surface 10u of the die 10A. When the molded body 41 is completely exposed from the die 10A, the upper punch 11 is moved upward as shown in FIG. Here, the die 10A is moved with the molded body 41 sandwiched between the lower surface 11d of the upper punch 11 and the upper surface 12u of the lower punch 12, and the upper punch 11 is moved in a subsequent process. At the same time, the upper punch 11 may be moved upward, or the upper punch 11 may be moved before the die 10A.

  Since the molded body 41 can be removed by moving the upper punch 11, the molded body 41 can be taken out by, for example, a manipulator.

  In the case of continuous molding, when the molded body 41 is removed and removed from the molding die 1, the formation of the molding space as described above → formation of the raw material powder into the molding space in forming the next molded body Filling, pressurizing, and taking out may be repeated.

  The shape of the molded body 41 manufactured through the above steps is a shape in which the inner peripheral shape of the die 10A and the shapes of the lower surface 11d of the upper punch 11 and the upper surface 12u of the lower punch 12 are transferred. That is, as shown in FIG. 1 (F), the upper side of the drawing in FIG. 1 is a chord, the opposite side (the lower side of the drawing in the drawing) is an arc, and a part of the arc is cut away in parallel with the chord. It is an arcuate (bow-shaped) columnar body. This molded body 41 serves as an outer core included in the reactor. In this molded body 41, the opposing surface pressed by the upper punch 11 does not slide into contact with the mold during pressurization or demolding, so that it is difficult to form a conductive portion through which soft magnetic particles are conducted.

<Other processes>
As another process, it is preferable to perform a heat treatment process for heating the molded body after the molding process in order to remove the strain introduced into the soft magnetic particles in the molding process.

  Since the higher the temperature of the heat treatment performed in the heat treatment step, the more the strain can be removed, the heat treatment temperature is preferably 300 ° C. or higher, particularly 400 ° C. or higher. From the viewpoint of suppressing thermal decomposition of the insulating coating coated with the soft magnetic particles, the upper limit of the heat treatment temperature is about 800 ° C. If it is such heat processing temperature, the distortion introduce | transduced into a soft-magnetic particle at the time of pressurization can be removed, and the hysteresis loss of a molded object can be reduced effectively.

  What is necessary is just to select the time which heat-processes suitably according to the said heat processing temperature and the volume of a molded object so that the distortion introduce | transduced into the soft-magnetic particle in the shaping | molding process may fully be removed. For example, in the above temperature range, it is preferably 10 minutes to 1 hour.

  The atmosphere at the time of performing the heat treatment may be in the air, but it is particularly preferable to apply in an inert gas atmosphere. Thereby, it can suppress that a coated soft magnetic particle is oxidized with oxygen in air | atmosphere.

<Effect>
According to embodiment mentioned above, there exist the following effects.

  (1) According to the above manufacturing method, when the reactor is assembled in the molding step, the facing surface of the outer core facing the inner core is pressed with the upper punch so that the facing surface is pressed or , Does not slidably contact the die when demolding. For this reason, the insulating coating of the coated soft magnetic powder on the facing surface is hardly damaged, and it is difficult to form a conducting portion where the soft magnetic particles are conducted. In other words, since the conductive part is difficult to be formed on the facing surface, when the reactor is assembled so that the facing surface is perpendicular to the direction of the magnetic flux and the coil is excited, eddy current is hardly generated on the surface of the facing surface. Loss can be reduced. Therefore, it is possible to manufacture an outer core that is effective for reducing the reactor loss.

  (2) Since the outer core manufactured by the above-described manufacturing method is effective in reducing the loss of the reactor, a low-loss reactor can be constructed.

<Modification>
Hereinafter, modifications of the manufacturing method according to the first embodiment will be described. The molding die 1 in the manufacturing method described above is such that the planar shape of the outer core is the dimension in the width direction along the opposite surface side on the opposite side of the outer core opposite to the side facing the inner core. Any shape of the upper punch 11, the lower punch 12, and the die 10A can be appropriately selected as long as an outer core having a small shape can be formed. In the following modification, an example in which a part of the molding die is different from the first embodiment will be described.

[Modification 1]
In the first modification, as shown in FIG. 2A, the shape of the upper punch 11 in the molding die 1 for molding the outer core is different from that of the first embodiment. However, the shapes of the die 10A and the lower punch 12 are the same as those in the first embodiment. Hereinafter, differences from the first embodiment will be described.

(Upper punch)
In this example, as shown in FIG. 2 (A), the center portion of the lower surface 11p of the upper punch 11 in the width direction (the left-right direction in the drawing) is arranged in the depth direction (the left and right direction in the drawing). The upper punch 11 having a convex portion protruding toward the lower punch 12 side is used over the direction perpendicular to the paper surface of FIG.

  Using the upper punch having the above shape, the molded body 42 is molded through the same molding process as in the first embodiment. Then, the upper punch 11 is moved upward as shown in FIG.

  As shown in FIG. 2 (F), the shape of the molded body 42 manufactured in this way is an opening on the paper surface of the drawing, and a part on the opposite side is cut away in parallel with the plane on the opening side. It is a substantially U-shaped (U-shaped) columnar body. This molded body 42 becomes an outer core included in the reactor. When the reactor is constructed with the molded body 42, the opening side of the molded body 42 is disposed so as to be connected to the inner core. In that case, the vicinity of the connecting surface of the molded body 42 (outer core) is allowed to be covered with the coil in the circumferential direction.

[Modification 2]
In the second modification, as shown in FIG. 3, the inner peripheral shape of the through hole 10 h provided in the die 10 </ b> A in the molding die 1 for forming the outer core is different from that in the first embodiment. However, the shapes of the upper and lower punches 11 and 12 are the same as those in the first embodiment. Hereinafter, differences from the first embodiment will be described.

(Die)
In this example, the die 10A of the molding die 1 has an inner peripheral shape of the die 10A (tapered hole 10c), the upper surface 10u side (lower end of the large rectangular hole 10p) of the die 10A is the long side, and the lower punch 12 side ( A die 10A having a trapezoidal shape (trapezoidal shape) having a short side at the upper end of 10r of the small rectangular hole is used.

  Using the die 10 </ b> A having the above shape, the molded body 43 is molded through the same molding process as that of the first embodiment. Then, the upper punch 11 is moved upward as shown in FIG.

  As shown in FIG. 3 (F), the shape of the molded body 43 thus manufactured is a trapezoid (trapezoidal shape) in which the upper side in the figure is the long side, the lower direction in the figure is the short side, and both sides are parallel. It is a columnar body. This molded body 43 becomes an outer core included in the reactor. When the reactor is constructed with the molded body 43, the long side of the molded body 43 is disposed on the inner core side of the reactor. The opposed surfaces on the long side of the molded body 43 are opposed to the end surfaces of the inner cores divided into left and right in the figure.

[Modification 3]
In Modification 3, with respect to the outer core of the first embodiment (FIG. 1), the opposing surface side rectangular surface having the opposing surface as a long side and the opposite side having the parallel surface opposite to the opposing surface as the long side. A method for manufacturing the outer core having at least one of the rectangular surfaces will be described. In this example, as shown in FIG. 4A, in the molding die 1 for molding the outer core, the shape of the die 10A and the position of the upper surface 12u of the lower punch 12 with respect to the die 10A are the first embodiment. And different. However, the shape of the upper punch 11 and the shape of the lower punch 12 and the thickness of the entire molded body to be molded are the same as in the first embodiment. Hereinafter, differences from the first embodiment will be described. Here, for convenience of explanation, the die 10A, the overall thickness of the molded body 44, and the thickness of each rectangular surface in FIG. 4 are exaggerated.

(Die)
In this example, as the die 10A, as shown in FIG. 4A, a large rectangular hole 10q having a thickness (in the vertical direction of the drawing in the drawing) larger than that of the first embodiment is used. The position of the lower surface 11d of the upper punch 11 with respect to the die 10A does not reach the lower end of the large rectangular hole 10q when the pressurization is completed because the thickness of the large rectangular hole 10q is increased. Therefore, the opposing surface side rectangular surface 44f having the opposing surface as its long side by the thickness of the large rectangular hole 10q, that is, the thickness between the lower surface 11d of the upper punch 11 and the lower end of the large rectangular hole 10q. Is formed in the molded body 44. That is, the thickness of the opposing surface side rectangular surface 44f (F in the same figure) is the thickness of the large rectangular hole 10q, more specifically, between the lower surface 11d of the upper punch 11 and the lower end of the large rectangular hole 10q. It can be adjusted appropriately according to the distance. Therefore, the thickness (depth) of the large rectangular hole 10q may be appropriately selected according to the desired thickness of the opposing surface side rectangular surface 44f. For example, the opposing surface side rectangular surface 44f can be thickened as the thickness of the large rectangular hole 10q of the die 10A is increased and the distance between the lower surface 11d of the upper punch 11 and the lower end of the large rectangular hole 10q is increased. Thus, it is preferable to select the thickness of the large rectangular hole 10q so that the thickness of the opposing-surface-side rectangular surface 44f is 0.3 mm or more and 2.0 mm or less. It is preferable to select it to be 5 mm or less. If the opposing surface side rectangular surface 44f is manufactured to have a thickness of 0.3 mm or more, the upper punch 11 can be sufficiently prevented from colliding with the tapered hole 10t on the inner peripheral surface of the die 10A. Further, by manufacturing the opposing surface side rectangular surface 44f to have a thickness of 2.0 mm or less, the coated soft magnetic powder on the opposing surface side can reduce the area in sliding contact with the die during pressurization or demolding. It is possible to suppress damage to the insulating coating.

(Lower punch)
Further, in this example, in the molding die 1, when forming the molding space 31 in the filling process, the position of the upper surface 12u of the lower punch 12 with respect to the die 10A is added to the descending amount of the die 10A during pressurization. The lower punch 12 is disposed so as to be positioned on the lower opening side from the upper end of the small rectangular hole 10s by a desired thickness of the opposite rectangular surface 44o in the molded body 44 to be manufactured. The thickness of the opposite rectangular surface 44o (F in the figure) of the manufactured molded body 44 can be appropriately adjusted at the position of the upper surface 12u of the lower punch 12 with respect to the small rectangular hole 10s. Therefore, the position of the upper surface 12u of the lower punch 12 may be appropriately selected according to the desired thickness of the opposite rectangular surface 44o. For example, by disposing the position of the upper surface 12u of the lower punch 12 with respect to the die 10A on the upper end side of the small rectangular hole 10s, the thickness of the opposite rectangular surface 44o can be reduced, and conversely the lower end side of the small rectangular hole 10s. By disposing on the (lower opening side), the thickness of the opposite rectangular surface 44o can be increased. Thus, it is preferable to appropriately select the position of the upper surface 12u of the lower punch 12 so that the thickness of the opposite rectangular surface 44o is 0.5 mm or more and t / 2 or less, and in particular, 1.0 mm or more. It is preferable to select so as to be t / 2 or less. Here, “t” refers to the thickness from the facing surface of the manufactured molded body 44 to the opposite end surface. If the opposite rectangular surface is manufactured to have a thickness of 0.5 mm or more, it is possible to sufficiently prevent the lower punch 12 from entering the inside of the die 10A more than the small rectangular hole 10s during pressurization. By manufacturing the opposite rectangular surface 44o so that the thickness thereof is t / 2 or less, the opposite rectangular surface with respect to the entire outer core does not become too large.

  As in this example, when manufacturing the molded body 44 having both the opposing rectangular surface 44f and the opposing rectangular surface 44o, the opposing rectangular surface 44f has a thickness of the opposing rectangular surface 44f. The distance between the lower end of the large rectangular hole 10q and the lower surface 11d of the upper punch 11 and the distance between the upper end of the small rectangular hole 10q and the upper surface 12u of the lower punch 12 are appropriately selected so as to be thinner than 44o. It is preferable to do. If the opposing surface side rectangular surface 44f is thin, when the reactor is constructed with the reactor, the opposing surface side arranged near the coil may reduce the sliding contact area with the die 10A during pressurization or demolding. It is possible to suppress damage to the insulating coating constituting the molded body. As a result, eddy current loss can be reduced.

  Using the molding die 1 described above, the molded body 44 is molded through the same molding process as in the first embodiment. When the pressurization is completed, the position of the upper surface 12u of the lower punch 12 with respect to the die 10A is positioned on the lower opening side from the upper end of the small rectangular hole 10s by the thickness of the opposite rectangular surface 44o of the molded body 44. Then, the upper punch 11 is moved upward as shown in FIG.

  As shown in FIG. 4 (F), the shape of the molded body 44 thus manufactured is such that the long side extends in the width direction from the upper side in the drawing to the opposite side (the lower side in the drawing). An opposing surface side rectangular surface 44f constituted by a rectangle, a long side of the rectangle as a chord, an arc on the opposite side, and a substantially arcuate shape in which a part of the arc is cut out parallel to the chord, It is a columnar body constituted by an opposite rectangular surface 44o constituted by a rectangle having one side formed by cutting out an arc. This molded body 44 becomes an outer core included in the reactor. In this compact 44, the reactor is constructed so that the surface pressed by the upper punch 11 becomes the opposing surface.

[Modification 4]
In the modification 4, as shown in FIG. 5A, in the molding die 1 shown in the modification 1, the thickness of the large rectangular hole 10q and the position of the upper surface 12u of the lower punch 12 with respect to the die 10A are modified. 3, and a part of the upper punch 11 is different from the first modification. That is, when the thickness of the large rectangular hole 10q is made thicker than that of the first embodiment and the first modification, and the molding space 31 is formed in the filling process, the position of the upper surface 12u of the lower punch 12 is the die 10A in pressurization. The lower punch 12 is arranged so as to be positioned on the lower opening side from the upper end of the small rectangular hole 10s by a desired thickness of the opposite rectangular surface 45o in the molded body 45 to be manufactured. Hereinafter, differences from Modification 1 will be described.

(Upper punch)
In this example, the upper punch 11 having a convex portion protruding toward the lower punch 12 is used as in the first modification. As shown in FIG. 5, the shape of the convex portion is a uniform rectangular surface 11q extending from the lower surface 11p of the upper punch 11 to the lower punch 12 side, and further formed from the rectangular surface 11q toward the lower punch 12 side. The bow shape is a string on the rectangular surface 11q side and an arc on the lower punch 12 side. In this convex part, the thickness of the rectangular surface 11q (the vertical direction in the figure) forms a linear region 45l in the opening of the manufactured molded body 45 (FIG. (F)). Therefore, the length of the straight region 45l can be appropriately selected depending on the thickness of the rectangular surface 11q.

  Using the upper punch 11 having the above shape, the molded body 45 is molded through the same molding process as in the first embodiment. When the pressurization is completed, the position of the upper surface 12u of the lower punch 12 with respect to the die 10A is positioned on the lower opening side from the upper end of the small rectangular hole 10s by the thickness of the opposite rectangular surface 45o of the molded body 45. Then, the upper punch 11 is moved upward as shown in FIG.

  As shown in FIG. 5 (F), the shape of the molded body 45 manufactured in this way is an opposing surface side rectangular surface 45f constituted by a rectangle having an opening in the upper surface of the drawing and having the linear region 45l. , An opposite rectangular surface composed of a substantially U-shape in which a part on the opposite side is cut out in parallel with the plane on the opening side, and a rectangle that uniformly protrudes in the opposite direction from one side formed by the notch It is a columnar body composed of 45o. This molded body 45 becomes an outer core included in the reactor. When the reactor is constructed with the molded body 45, the flat surface (connecting surface) on the opening side of the molded body 45 is arranged so as to be connected to the inner core. In that case, as in the first modification, the vicinity of the connection surface of the opposing surface side rectangular surface 45f of the molded body 45 (outer core) is allowed to be covered with the coil in the circumferential direction.

[Modification 5]
In the modified example 5, as shown in FIG. 6A, in the molding die 1 shown in the modified example 2, the thickness of the large rectangular hole 10q and the position of the upper surface 12u of the lower punch 12 with respect to the die 10A are modified. Same as 3. That is, when the thickness of the large rectangular hole 10q is made thicker than that of the modified example 2 and the molding space 32 is formed in the filling process, the position of the upper surface 12u of the lower punch 12 corresponds to the descending portion of the die 10A during pressurization. In addition, the lower punch 12 is arranged so as to be positioned on the lower opening side from the upper end of the small rectangular hole 10s by a desired thickness of the opposite rectangular surface 46o in the molded body 46 to be manufactured.

  The molded body 46 is molded through the same molding process as in the first embodiment. When the pressurization is completed, the position of the upper surface 12u of the lower punch 12 with respect to the die 10A is positioned on the lower opening side from the upper end of the small rectangular hole 10s by the thickness of the opposite rectangular surface 46o of the molded body 46. Then, as shown in FIG. 6E, the upper punch 11 is moved upward, and the molded body 46 is taken out.

  As shown in FIG. 6 (F), the shape of the molded body 46 thus manufactured is such that the opposite surface is a long side from the upper side in the drawing to the opposite side (the lower side in the drawing). The opposing surface side rectangular surface 46f, a trapezoid whose long side is one side of the rectangle, and the opposite rectangular surface 46o whose one side (long side) is the short side of the trapezoid. . This molded body 46 becomes an outer core included in the reactor. When the reactor is constructed with this molded body 46, the long side of the molded body 46 is arranged on the inner core side included in the reactor as in the second modification. That is, the end surface of each inner core faces the opposing surface on the long side of the molded body 46 separately on the left and right in the figure.

<Effect>
According to the above-described modification, the molded body manufactured using the punch or die having the above-described shape is effective for reducing the reactor loss, and thus can be suitably used for the outer core of the reactor. . Further, by manufacturing the molded body so as to have a rectangular surface on the opposed surface side, collision between the upper punch and the tapered hole on the inner peripheral surface of the die can be prevented during pressurization. Therefore, the molding die is hardly damaged, and the life of the molding die is hardly reduced. In addition, during pressurization, it is easy to apply pressure to the molded body, and a high-density molded body can be manufactured. When manufacturing so as not to have a rectangular surface on the opposite side, when the pressurization process is completed so that the upper surface of the lower punch does not enter the inside of the die (upper punch side) from the small rectangular hole, It is necessary to precisely align the upper surface of the upper surface with the upper end of the small rectangular hole. On the other hand, when manufacturing so as to have a rectangular surface on the opposite side, when pressing is completed, the upper surface of the lower punch is positioned in the middle of the small rectangular hole. It can be sufficiently prevented from entering (upper punch side). Therefore, when manufacturing so as to have the opposite rectangular surface, it is more difficult to position the upper surface of the lower punch on the opposite side of the opposing surface of the outer core than when the upper surface of the lower punch is positioned strictly. It is possible to prevent formation of sharp corners that are easily chipped at both ends in the width direction. That is, the molding speed can be increased during continuous molding, and the productivity is excellent.

<< Embodiment 2 >>
Embodiment 2 demonstrates an example of the reactor which provides the outer core manufactured by the above-mentioned manufacturing method. That is, the reactor of the present invention is characterized in that the outer core manufactured by the above-described manufacturing method is used for the outer core provided in the reactor. The other configuration is the same as that of the conventional reactor described with reference to FIGS. 7 and 8, but here, the configuration similar to that of the conventional reactor will be described below. As the outer core, a reactor including the outer core manufactured by the manufacturing method described in the first embodiment will be described as an example.

[Reactor]
As shown in FIG. 7, the reactor 100 includes a coil 105, an inner core 101 c disposed inside the coil 105, and an outer core 101 e exposed from the coil 105 as main constituent members. The exposure mentioned here includes a case where the entire outer core 101e is exposed and a case where a part of the outer core is surrounded by a turn as in the case where the outer core is U-shaped.

[coil]
The coil 105 has a pair of coil elements 105a and 105b formed by spirally winding one continuous winding 105w. Both coil elements 105a and 105b are arranged side by side so that the respective axial directions are parallel. Further, by positioning the winding end on one end side in the axial direction of the coil 105 and bending the winding on the other end side to provide the rewinding portion 105r (FIG. 8), one coil element 105a, 105b is provided. The winding is formed. And the coil | winding uses the covered rectangular wire which gave the enamel coating for insulation to the rectangular copper wire. Each of the coil elements 105a and 105b is formed by winding a coated rectangular wire edgewise. In addition to the flat wire, various windings having a circular cross section and a polygonal cross section can be used. The pair of coil elements 105a and 105b may be separately manufactured, and the ends of the windings of both the coil elements 105a and 105b may be connected by welding or the like.

[core]
The core 101 is an annular member composed of an inner core 101c and an outer core 101e.

  The inner core 101c includes a magnetic core piece 101m and a gap portion g provided between the core pieces 101m for adjusting the inductance at a portion where a coil is disposed on the outer periphery. As the gap material disposed in each gap portion g, a plate-like material made of a nonmagnetic material such as alumina can be used. The inner core 101c is configured by alternately laminating core pieces 101m and gap portions g and joining them with an adhesive or the like. In this example, a pair of inner cores 101c are arranged in parallel. As the core piece 101m, a compacted body obtained by press-molding a coated soft magnetic powder containing iron, or a laminated body obtained by laminating a plurality of electromagnetic steel sheets can be used.

  The outer core 101e is a molded body obtained by press-molding the coated soft magnetic powder and obtained by the above-described manufacturing method. The shape in plan view is a substantially bow shape (bow shape) having a string and an arc. In the substantially arcuate (bow-shaped) outer core 101e, the string side is arranged on the inner core 101c side. Then, when the surface facing the cooling base in the constituent members of the reactor is the base surface (the lower surface in FIGS. 7 and 8), the base surface of the outer core 101e is positioned substantially at the same position as the base surfaces of the coil elements 105a and 105b. Further, the base surface of the outer core 101e protrudes downward (cooling base side) with respect to the base surface of the inner core 101c.

  In order to configure the core 101, the pair of inner cores 101c and the pair of outer cores 101e are connected to form a ring. For the connection, an adhesive or the like can be used, and both the cores 101c and 101e may be directly connected or indirectly connected via a gap material similar to the gap part g. In this example, four core pieces 101m and three gap portions g are used as the inner core 101c, but the number of divisions of the core 101 and the number of gap portions g can be selected as appropriate.

<Insulator>
The insulator 107 is a member that ensures insulation between the core 101 and the coil 105, and is used as necessary. The insulator 107 includes a cylindrical portion 107b that covers the outer periphery of the inner core 101c of the core 101, and a pair of flange portions 107f that are in contact with the end face of the coil. The tubular portion 107b can easily cover the outer periphery of the inner core 101c by joining the half-cut square tube pieces together. The flange portion 107f is a member configured by a pair of rectangular frames integrated in a parallel state and disposed at one end portion of the tubular portion 107b. For the insulator 107, an insulating resin such as a polyphenylene sulfide (PPS) resin, a liquid crystal polymer (LCP), or a polytetrafluoroethylene (PTFE) resin can be used.

<Effect>
The reactor according to the embodiment described above includes an outer core that hardly generates eddy currents on the facing surface facing the side facing the inner core, so that iron loss can be reduced even when the coil is excited by high-frequency alternating current. .

《Test example》
As test examples, the following samples 1 to 4 were prepared, and the test described below was performed for the magnetic properties of each sample.

[Sample 1]
An iron powder having a purity of 99.8% or more prepared by a water atomization method was prepared as soft magnetic particles. The soft magnetic particles had an average particle size of 50 μm and an aspect ratio of 1.2. This average particle size was determined from the particle size of particles in which the sum of masses from particles with small particle sizes reached 50% of the total mass, that is, 50% particle size, in the particle size histogram. Then, the surface of the metal particles was subjected to a phosphate chemical conversion treatment to form an insulating coating made of iron phosphate, thereby producing coated soft magnetic particles. The insulating coating substantially covered the entire surface of the soft magnetic particles, and the average thickness was 20 nm. The aggregate of the coated soft magnetic particles is a coated soft magnetic powder as a constituent material of the molded body.

  A lubricant containing zinc stearate is added to the coated soft magnetic powder so that the content is 0.6% by mass to prepare a mixture, and the mixture is a mold having a predetermined shape shown in the first embodiment ( The molded body 41 having the shape shown in FIG. 1 was produced by injecting into FIG. 1) and press-molding it under a pressure of 588 MPa.

[Sample 2]
Sample 2 differs from Sample 1 in the planar shape of the molded body. That is, molding is performed using a molding die different from the sample 1. Here, a molded body having the same shape as the molded body 44 shown in FIG. 4F was manufactured using a mold having a predetermined shape shown in Modification 3 (FIG. 4). When the thickness of the molded body was measured, the thickness of the entire molded body 44 was 24 mm, the thickness of the opposing surface side rectangular surface 44 f was 1.5 mm, and the thickness of the opposite rectangular surface 44 o was 10 mm. Met.

[Sample 3]
The sample 3 uses a mold having the same shape as that of the sample 2, but the thicknesses of the opposing-side rectangular surface 44f and the opposite-side rectangular surface 44o of the molded body 44 are different from those of the sample 2. That is, it was produced using a molding die 1 different from the sample 2 in the thickness of the large rectangular hole 10q and the position of the upper surface 12u of the lower punch 12 with respect to the die 10A. When the thickness of the molded body 44 was measured, the overall thickness of the molded body 44 was 24 mm, the thickness of the opposing surface side rectangular surface 44 f was 5 mm, and the thickness of the opposite rectangular surface 44 o was 1 mm. there were.

[Sample 4]
The sample 4 is different from the sample 1 in the surface to be pressed with a punch. That is, the sample 2 was formed by pressing the surface (in the direction of the white arrow in FIG. 8) that is substantially perpendicular to the magnetic flux with the upper and lower punches.

[Evaluation]
Samples 1 to 4 manufactured through the above steps and a plurality of compacted cuboid compacts manufactured under the same conditions using the same material as the sample are heat-treated at 400 ° C. for 30 minutes in a nitrogen atmosphere. The heat treatment material was obtained. A test magnetic core was manufactured by combining the obtained heat treatment material of each sample and the heat treatment material of the green compact in a ring shape, and the following magnetic property values were measured. At that time, Samples 1 to 3 were combined in an annular shape so that the pressing surface of the molded body opposed to the rectangular parallelepiped.

[Magnetic property test]
A measuring member for measuring magnetic characteristics was prepared by arranging a coil composed of a winding (each sample having the same specification) on each test magnetic core. For this measurement member, the eddy current loss We (W) of the sample at an excitation magnetic flux density Bm: 1 kG (= 0.1 T) and a measurement frequency: 5 kHz was determined using an AC-BH curve tracer. The results are shown in Table 1.

〔result〕
Samples 1 to 3 had smaller eddy current loss than Sample 4. This is because when the samples 1 to 3 are manufactured, the surface through which the magnetic flux passes substantially orthogonally is pressed, and the pressing surface does not slide into contact with the die during pressing or demolding. For this reason, the insulating coating of the coated soft magnetic powder of the constituent material on this surface is not damaged, and it is difficult to form a conduction portion where the soft magnetic particles are conducted. Therefore, it is considered that eddy current loss can be reduced because eddy current hardly occurs on the pressing surface. Samples 1 and 2 had smaller eddy current loss than sample 3, and sample 1 and sample 2 had equivalent eddy current loss. This is because sample 1 does not have a rectangular surface on the opposed surface side, and sample 2 has a thinner rectangular surface on the opposed surface side than sample 3; As compared with, there were almost no or few portions that were in sliding contact with the mold on the opposite surface side during molding, particularly at the time of demolding. That is, it is considered that the damage to the insulating film on the facing surface arranged in the vicinity of the coil can be reduced, and the occurrence of eddy currents generated in the circumferential direction in Samples 1 and 2 can be further suppressed than in Sample 3.

  The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist of the present invention. For example, in the modified examples 3 to 5, although both the opposing surface side rectangular surface and the opposite rectangular surface are provided, it is possible to provide either one. Moreover, the opening part of the molded object 45 in the modification 4 may be comprised only in the curve area | region, without forming the linear area | region 45l. In that case, like the convex part similar to the modified example 2 (FIG. 2), the upper part having a convex part constituted by a bow shape in which a part of the lower surface 11d of the upper punch 11 is a chord and the lower punch 12 side is an arc. A punch 11 may be used.

  The outer core of the present invention can be suitably used for a booster circuit such as a hybrid vehicle and a reactor used in power generation / transforming equipment. Moreover, the manufacturing method of the outer core of this invention can be utilized suitably for manufacture of the outer core of a reactor. The reactor of the present invention can be used for components of a power conversion device such as a DC-DC converter mounted on a vehicle such as a hybrid vehicle, an electric vehicle, or a fuel cell vehicle.

DESCRIPTION OF SYMBOLS 1 Mold for die 10A Die 10b, 10h Through-hole 10u Upper surface 10p, 10q Large rectangular hole 10r, 10s Small rectangular hole 10c, 10t Taper hole 11 Upper punch 11d, 11p Lower surface 11q Rectangular surface 12 Lower punch 12u Upper surface 31, 32 Molding space 41, 42, 43, 44, 45, 46 Molded body 44f, 45f, 46f Opposing surface side rectangular surface 44o, 45o, 46o Opposite side rectangular surface 45l Linear region P Raw material powder 100 Reactor 101 Core 101c Inner core 101e Outer core 101m Core piece g Gap part 105 Coil 105a, 105b Coil element 105w Winding 105r Rewinding part 107 Insulator 107b Cylindrical part 107f Gutter part

Claims (3)

A coil in which a pair of coil elements in which windings are spirally wound are connected in parallel to each other, a pair of inner cores arranged inside each coil element, and exposed from the coils and connected to each inner core Then, the outer core manufacturing method for manufacturing the outer core in a reactor comprising the inner core and a pair of outer cores forming an annular core by pressure molding,
The outer core includes a connection surface with the inner core, and has a facing surface facing the other outer core with the inner core sandwiched therebetween.
When the outer core is viewed in plan from the axial direction of the annular core, the planar shape of the outer core is such that the opposite side of the outer core is opposite to the opposite surface rather than the opposite side of the outer core to the inner core. The shape along the width direction is small,
As a raw material powder for the outer core, a preparation step of preparing a coated soft magnetic powder comprising a plurality of coated soft magnetic particles in which a soft magnetic particle is coated with an insulating coating;
A forming space formed by a relatively movable columnar first punch and a cylindrical die is filled with the coated soft magnetic powder, and the columnar second disposed opposite to the first punch and the first punch. A molding step of press-molding the coated soft magnetic powder in the molding space with a punch,
In the molding step, the outer core is manufactured by pressurizing the facing surface of the outer core with the second punch.   The method for manufacturing an outer core according to claim 1, wherein the soft magnetic particles are pure iron. The method for producing an outer core according to claim 1 or 2, wherein a planar shape of the outer core is any one of the following (A) to (C).
(A) A bow shape in which the opposite side of the outer core to the inner core is a chord and the opposite side is an arc.
(B) A trapezoid having a long side on the side of the outer core facing the inner core.
(C) A U shape in which the opposite side of the outer core to the inner core is an opening.

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