JP2011253982A - Reactor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reactor with an excellent manufacturing efficiency while ensuring desired inductance performance by eliminating use of a gap plate and an adhesive layer.SOLUTION: A reactor 10 includes a plurality of magnetic cores 1, 2 that are joined through joining portions 3 each having a smaller cross section than those of the magnetic cores 1, 2 and being formed from the same material as the magnetic cores 1, 2. The whole reactor is formed into a substantially annular shape.

Description

  The present invention relates to a reactor constituting a power conversion circuit.

  The reactor of the power conversion circuit is generally accommodated in, for example, a housing in a posture in which coils are formed in two longitudinal portions of a reactor core that is generally annular in plan view. A typical reactor core is made up of a magnetic core material consisting of a stack of magnetic steel sheets or a dust core, and a non-magnetic gap plate or spacer is interposed between each core material. A reactor is formed by adhering and fixing a plate and the core material with an adhesive. Since the magnetic cores try to attract each other by a magnetic attractive force, a gap length having a desired thickness can be guaranteed by interposing this gap plate or spacer between the magnetic cores.

  The general structure of a conventional reactor will be described with reference to FIG. 7. A core plate a having a substantially U shape in plan view (U type core) and a core b having a rectangular shape in plan view (I type core) are gap plates. An insulating bobbin (not shown) or the like is formed on the longitudinal part of the adhesive layer d via c, and a coil (not shown) is formed around the bobbin. As a conventional published technique related to the reactor core having such a configuration, for example, a reactor core disclosed in Patent Document 1 can be cited.

  By the way, when the core material and the gap plate are bonded, the durability of the reactor is lowered due to the deterioration of the adhesiveness. Furthermore, due to the manufacturing tolerance of both the core material and the gap plate and the manufacturing tolerance of the adhesive layer, the average magnetic path length of the reactor in which these members are assembled changes, and a desired inductance cannot be obtained. Problems can arise.

  In other words, the conventional reactor has a structure in which the magnetic core material and the gap plate are bonded and fixed via an adhesive layer. The manufacturing tolerance of this adhesive layer is the same as the manufacturing tolerance of other core materials. This is extremely difficult to eliminate, and as described above, the deterioration of the adhesive layer is significant compared to other members, so that this adhesive layer determines the durability of the reactor. It was a cause. In addition, in the reactor of the said patent document 1, it adds that it is difficult to ensure predetermined | prescribed magnetic path length easily in the state in which the electric current is not supplied with the manufactured reactor.

  In addition, it is necessary to fix the magnetic core before the adhesive layer is cured, and there is a problem that a jig for that purpose is required, and that the core fixing operation until curing is required. More specifically, in addition to the magnetic core, the gap plate is also fixed with a jig, and the adhesive layer is formed in a posture that secures a space for the adhesive layer so that a desired thickness is formed. It is necessary to

  Furthermore, in the case where the reactor is mounted in an engine room such as a hybrid vehicle, there is a possibility that it will be placed in a cold cycle environment within a range of about −40 ° C. to 150 ° C. due to a change in its use environment. In the reactor in which the gap plate is interposed, there may be a problem that peeling is likely to occur at the bonding portion between the core material and the gap plate. This is because the core material, gap plate, and adhesive layer have different linear expansion coefficients, resulting in a difference in thermal expansion between the members. The structurally weak adhesive layer is caused by this thermal expansion difference and repeated thermal stress. It is because it becomes easy to peel.

JP 2004-241475 A

  The present invention has been made in view of the above-described problems, and an object thereof is to provide a reactor excellent in manufacturing efficiency while eliminating a gap plate and an adhesive layer and ensuring desired inductance performance.

  In order to achieve the above-described object, the reactor according to the present invention is configured such that a plurality of magnetic cores are connected via a connecting portion made of the same material as the magnetic core with a cross-sectional area smaller than the cross-sectional area of the magnetic core. Is formed.

  The reactor of the present invention eliminates the hard gap plate and the adhesive layer arranged between the reactor cores constituting the conventional reactor, and instead, a plurality of magnetic cores have a smaller cross section than this magnetic core. The magnetic core and the same material are connected via a connecting portion to form a substantially annular shape.

  Here, the magnetic core refers to a U-shaped core or an I-shaped core having magnetism, and a reactor can be constituted by two U-shaped cores. A reactor can also be formed by interposing an I-type core. Further, the magnetic core may be formed from a laminate formed by laminating silicon steel plates, or a pressure formed by pressing a soft magnetic metal powder or a magnetic powder coated with a soft magnetic metal powder with a resin binder. Although it may be formed from a powder magnetic core, it is preferable that the magnetic core is formed from a powder magnetic core in consideration of manufacturing efficiency.

  Here, the connecting portion can be formed integrally with the magnetic core. In other words, a magnetic ring is filled into a cavity of a mold in which the overall shape of the reactor core is defined, and by pressing, a substantially annular reactor core consisting of a connecting portion that connects a plurality of magnetic cores is formed at once. can do.

  Moreover, the connection part should just be the cross-sectional area smaller than the cross-sectional area of a magnetic core, for example, the form which connects magnetic cores by one connection part of a relatively small cross-sectional area may be sufficient. And the form which connects magnetic cores by a some connection part may be sufficient (the sum total of the cross-sectional area of a some connection part is smaller than the cross-sectional area of a magnetic core).

  More specifically, since the connecting portion is made of the same material as the magnetic core, the connecting portion itself has magnetism, and therefore, a conventional reactor core that forms a gap with a nonmagnetic gap plate or the like. In order to ensure the same level of inductance performance, the length and cross-sectional area of the connecting part are adjusted so that the magnetic resistance of the gap is the same as that of the gap secured by the conventional reactor core gap plate. Need to be done.

  According to the reactor core formed by integrally molding the magnetic core and the connecting part, the gap plate and adhesive layer can be eliminated from the reactor components simply by improving the mold cavity to the overall shape of the reactor core to be manufactured. However, the gap thickness can be precisely managed by the cavity shape. In addition, since the substantially annular reactor can be manufactured at once by pressurization in the mold, it is possible to manufacture the reactor in a very short time, and the reactor manufacturing efficiency can be dramatically improved.

  In addition, the number of parts can be reduced by eliminating the gap plate and the adhesive layer, and the manufacturing cost can be greatly reduced by reducing the material cost and improving the manufacturing efficiency described above.

  Further, a part or all of each of the magnetic core and the connecting portion may be assembled with each other to form a reactor core.

  In this form of the reactor core, a form in which the magnetic core and the connecting part are respectively assembled, or a form in which one magnetic core and one connecting part are integrally formed, and the units are connected to each other to form a substantially annular core. Etc.

  For example, in a reactor core in which two U-type cores that are magnetic cores, two I-type cores interposed between the U-type cores, and a connecting portion connecting these U-type cores and I-type cores, A mold core, an I-type core, and a connecting part are separated from each other and assembled together to form a reactor core, for example, a U-shaped core and a connecting part are integrally molded, and this connecting part A form in which a reactor core is formed by assembling an I-type core can be exemplified.

  Here, there are various varieties such as a form in which the magnetic core and the connecting part are fitted to each other, a form to be screwed to each other, and a form to be pinned.

  Moreover, in the reactor mentioned above, the insulating resin mold body may be formed around the substantially annular magnetic core as in a conventional reactor.

  The insulating resin mold body ensures insulation between the magnetic core and the coil formed on the outer periphery thereof.

  Further, a part of the formed resin mold body is interposed in the gap between the adjacent magnetic cores, so that a gap made of the resin mold body is formed.

  By interposing the resin mold body in the gap, the rigidity (strength) of the reactor can be remarkably increased as compared with the reactor in which the gap region around the connecting portion is composed of only air.

  Further, after forming a resin mold body that guarantees insulation between the coil and the magnetic core on the outer periphery of the magnetic core and forming the coil around the periphery, a sealing resin body having excellent heat dissipation may be formed on the outer periphery. Of course.

  As can be understood from the above description, according to the reactor of the present invention, it is possible to precisely secure a gap having a desired thickness while eliminating the adhesive layer and gap plate of the reactor having the conventional structure, and manufacturing. Manufacturing costs can be greatly reduced by improving efficiency and reducing the number of parts.

It is a perspective view of one embodiment of a reactor of the present invention. (A) is a perspective view of other embodiment of the reactor of this invention, (b) is the figure explaining the fitting structure of the division body. (A) is the schematic diagram explaining the relationship of the cross-sectional area of a magnetic core and a connection part, (b) is the schematic diagram explaining the relationship between the length of the gap in the reactor structure of this invention, and the cross-sectional area of a connection part. (C) is the schematic diagram explaining the relationship between the length of the gap and the cross-sectional area of a connection part in the conventional reactor structure. It is a perspective view of other embodiments of the reactor of the present invention. It is a perspective view of further another embodiment of the reactor of this invention. It is the graph which showed the relationship between the cross-sectional area and length (gap thickness) of a connection part for satisfying fixed inductance performance. It is the perspective view explaining the general structure of the conventional reactor.

  Embodiments of the present invention will be described below with reference to the drawings. In the illustrated example, the illustration of the coils constituting the reactor is omitted. Further, the number and form of the magnetic core constituting the reactor is not limited to the illustrated example, the form including only two U-type cores, two or four I-type cores, and eight or more I-type cores Of course, it may be a form.

  1 and 2 are views showing an embodiment of a reactor, FIG. 3a is a schematic diagram illustrating the relationship between the cross-sectional areas of a magnetic core and a connecting portion, and FIG. It is the schematic diagram explaining the relationship of the width | variety of a part.

  A reactor 10 shown in FIG. 1 includes two U-shaped magnetic cores 1 and 1 in plan view, six I-type magnetic cores 2 disposed in plan view therebetween,. 2, the cross-sectional area is relatively smaller than that of the magnetic cores 1 and 2, and the connecting portions 3,... Made of the same material as the magnetic cores 1 and 2 are roughly configured, and the whole has a substantially annular shape.

  Here, the magnetic powder forming the U-type and I-type magnetic cores 1 and 2 and the connecting portion 3 is a soft magnetic metal powder or a magnetic powder coated with a soft magnetic metal powder with a resin binder. Metal powders include iron, iron-silicon alloys, iron-nitrogen alloys, iron-nickel alloys, iron-carbon alloys, iron-boron alloys, iron-cobalt alloys, iron-phosphorus alloys, iron -Nickel-cobalt alloys and iron-aluminum-silicon alloys can be used. Soft magnetic metal oxide powders may be used, and examples thereof include manganese-based, nickel-based, and magnesium-based ferrites.

  A reactor 10 shown in FIG. 1 is molded at once by filling the magnetic powder in a cavity of a mold (not shown) and press-molding it.

  As shown in FIGS. 1 and 3a, the connecting portion 3 having a cross-sectional area A2 smaller than the cross-sectional area A1 of the magnetic cores 1 and 2 connects the magnetic cores 1 and 2 or the magnetic cores 2 and 2, A space is formed on the side of the connecting portion 3, and this is a gap G.

  On the other hand, the reactor 10A shown in FIG. 2a is not formed all at once, but is a U-shaped split body 1A in which a U-shaped magnetic core and a connecting portion 3 'are integrated, and a U-shaped without a connecting portion. A magnetic core divided body 1B is composed of a divided body 2A in which an I-type magnetic core and a connecting portion 3 ′ are integrated.

  The divided body 1A is provided with fitting protrusions 6 on the end surfaces of the two connecting portions 3 ′, and these are fitted into the fitting grooves 5 formed at the end of the divided body 2A. Similarly, the fitting protrusion 6 is also provided on the end face of the connecting portion 3 ′ of the divided body 2A, and this is fitted in the fitting groove 5 of the adjacent divided body 2A. Yes. Although not shown in the drawings, a fitting groove is also formed in the end face of the divided body 1B, and the fitting protrusion 6 of the adjacent divided body 2A is fitted here, so that the abbreviation shown in FIG. An annular reactor 10A is formed.

  Here, the relationship between the length of the gap and the cross-sectional area of the connecting portion will be described with reference to FIGS. 3b shows the reactor structure of the present invention, and FIG. 3c shows a conventional reactor structure.

  In the conventional reactor shown in FIG. 3c, the gap is formed by a non-magnetic gap plate GI or the like, thereby guaranteeing the inductance performance of the reactor. On the other hand, in the reactor of the present invention shown in FIG. 3B, such a gap plate and an adhesive layer that connects the gap plate and the magnetic core are eliminated, and instead, the magnetic core 2 and the same material have a relatively sectional area. The magnetic cores 2 and 2 are connected by a small connecting portion 3, and gaps G and G are formed in two spaces on the side of the connecting portion 3.

Here, in the conventional reactor shown in FIG. 3c, the magnetic resistance R _gap in the gap plate GI can be expressed by the following equation (1).
R _gap = t / (μoS) (Equation 1)
Here, μo is the vacuum permeability.

On the other hand, the magnetic resistance R _gap ′ of the gap portion of the reactor shown in FIG. 3B is the sum of the magnetic resistance of the two gaps G and the magnetic resistance of the connecting portion 3, and the total area of the areas S1 ′ of the two gaps G is S1, When the area of the connecting portion 3 is S2 (S1 + S2 = S), the relative permeability of the connecting portion (core) is μs, and the length of the gap G is t1, the magnetic resistance of the gap G: Ra = t1 / (μoS1 ), The magnetic resistance of the connecting portion 3 is Rc = t1 / (μoμsS2). From these, the magnetic resistance R _gap ′ of the gap portion of the reactor shown in FIG. 3B can be expressed by the following equation.
R _gap '= RaRc / (Ra + Rc) = t1 / μo (μsS2 + S1) (Formula 2)

In order to obtain an inductance equivalent to that of a reactor having a conventional structure, it is only necessary that the magnetic resistances R _gap and R _gap ′ are equal.
t1 = ((μs−1) S2 + S) t / S (Equation 3)

  By adjusting the length of the connecting portion t2 and the area S2 so as to satisfy the above equation 3, inductance performance equivalent to that of the reactor having the conventional structure can be obtained.

  In both reactors 10 and 10A shown in FIGS. 1 and 2, the lengths of the connecting portions 3 and 3 ′ are defined by the accuracy during molding, and the desired thickness of the gap G is determined by the length of the connecting portions 3 and 3 ′. Is guaranteed with high accuracy. Therefore, it has a gap with higher precision thickness with high production efficiency compared to conventional reactors, where the thickness accuracy of the gap depends on the thickness control of the adhesive layer, which takes time to manage the accuracy. Reactor is obtained.

  FIG. 4 shows another embodiment of the reactor. In the illustrated reactor 10B, an insulating resin mold body 4 is formed on the outer periphery of the reactor 10 shown in FIG. 1, and a coil (not shown) is formed on the outer periphery, thereby ensuring insulation between the coil and the magnetic core. It is. In addition, you may further comprise the sealing resin body not shown excellent in heat dissipation in the outer periphery of the coil formed in the circumference | surroundings of the resin mold body 40. FIG.

  FIG. 5 shows still another embodiment of the reactor. A reactor 10C shown in the figure is a unit in which a magnetic core and a connecting portion are integrally formed in the same manner as the reactors 10 and 10B. The connecting portion 3A is composed of two connecting portions 3 and 3. The sum of the cross-sectional areas of the two connecting portions 3 and 3 is smaller than the cross-sectional area of the magnetic cores 1 and 2, and the gap G is larger than that of the one connecting portion 3 of the reactor 10 shown in FIG. The rigidity of the connecting portion to be formed can be increased. In addition, the form which comprises one gap from three or more connection parts may be sufficient. Further, like the reactor 10B, a resin mold body may be formed around the reactor 10C, and a sealing resin body may be further formed around the coil formed on the outer periphery thereof.

[Verification of the relationship between the cross-sectional area of the connecting part and the length of the gap (gap thickness) to satisfy a certain inductance performance and the result]
The inventors of the present invention relate to a reactor provided with a connecting portion having magnetism in the gap as shown in the figure, and satisfy an inductance performance equivalent to that of a conventional reactor not including this connecting portion (consisting of a nonmagnetic gap plate and an adhesive layer). The relationship between the cross-sectional area of the connecting portion and its length (that is, the gap thickness) was verified.

  In the reactor structure of the present invention, since the magnetic coupling portion is disposed in the gap, the reactor structure should not have the same magnetic resistance as a conventional reactor that does not include the coupling portion formed of the magnetic core in the gap. Inductance performance equivalent to that of a conventional reactor cannot be obtained. That is, it is necessary to adjust the length of the gap and the cross-sectional area of the connecting portion so as to have the same magnetic resistance as that of the conventional reactor.

  In the case where the height of the connecting portion is the same as the height of the magnetic core as in each of the illustrated reactors, the width and length (gap thickness) of the connecting portion are increased or decreased in order to guarantee the same inductance as the conventional reactor. Since it is necessary to adjust, the correlation between the two has been verified.

The verification result is shown in FIG. In the figure, the vertical axis represents the cross-sectional area of the connecting portion, when the cross-sectional area of ^{1mm 2, 4mm 2, 9mm 2} , both the length of the connecting portion to ensure an equivalent inductance It is what I have sought.

As a result of the verification, the gap lengths of 2.4 mm, 3.8 mm, and 6.2 mm are obtained for the cross-sectional areas of 1 mm ² , 4 mm ² , and 9 mm ² , respectively.

  Then, when each verification result is dropped into the coordinate system shown in the drawing and these correlation graphs are created, it can be understood that the cross-sectional area of the connecting portion shows a linear correlation with the gap length as a variable.

  That is, when the reactor is manufactured with the same height of the magnetic core and the connecting portion, if the magnetic resistance of the gap portion satisfying the desired inductance performance is determined, the width of the connecting portion formed in the gap portion is determined. Both lengths must be increased or decreased in proportion. This indicates that, for example, when trying to increase the width of the connecting portion in order to increase the rigidity of the gap portion, it is necessary to increase the length of the connecting portion in accordance with the increase in the width. This adjustment of the length of the connecting portion is governed by the maximum critical dimension of the reactor, which indicates that the rigidity of the connecting portion and the overall size are closely related.

  According to the reactor of the present invention, the gap plate and the adhesive layer, which are the constituent members of the conventional reactor, are abolished. It is possible to eliminate the difficulty of surface management and thickness accuracy management such as the prolongation of manufacturing time and the decrease in manufacturing yield due to this. In other words, the reactor according to the present invention greatly improves the thickness management accuracy of the gap in the manufacturing process, and also greatly improves the manufacturing efficiency. The improvement of the manufacturing efficiency, the manufacturing yield, and the number of parts Together with this reduction, the manufacturing cost can be greatly reduced.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. They are also included in the present invention.

DESCRIPTION OF SYMBOLS 1 ... Magnetic core (U type), 1A, 1B ... Divided body of magnetic core (U type), 2 ... Magnetic core (I type), 2A ... Divided body of magnetic core (I type), 3, 3 '... Connection 4, resin mold body, 5 ... fitting groove, 6 ... fitting projection, 10, 10A, 10B, 10C ... reactor, G ... gap

Claims (5)

  A reactor in which a plurality of magnetic cores are connected to each other through a connecting portion made of the same material as the magnetic core with a cross-sectional area smaller than the cross-sectional area of the magnetic core.   The reactor according to claim 1, wherein the plurality of magnetic cores and a connecting portion that connects the magnetic cores are integrally formed.   The reactor according to claim 1, wherein a part or all of each of the magnetic core and the connecting portion is assembled to each other.   The reactor according to claim 1, wherein an insulating resin mold body is formed around the substantially annular magnetic core.   The reactor according to claim 4, wherein the resin mold body forms a gap between adjacent magnetic cores.

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