JP2018060831A - Electric reactor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric reactor in which a heat evolution in a coil is reduced.SOLUTION: An electric reactor comprises U-shaped cores 3a and 3b formed by a plurality of leg parts 71a, 71b, 72a, and 72b and a plurality of yoke parts 8a and 8b; coils 4a and 4b wound concentrically along an axial direction of the leg parts 71a, 71b, 72a, and 72b; and magnetic shields 61a, 61b, 62a, and 62b provided so as to cover the coils 4a and 4b. The coils 4a and 4b is wound to the leg parts 71a, 71b, 72a, and 72b, and each of coils 4a and 4b generates a magnetic flux in a direction where the generated magnetic flux is reacted. The magnetic shields 61a, 61b, 62a, and 62b are arranged in a region where the magnetic flux generated from each coil is reflected and a space between the coils 4a and 4b.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a reactor.

  Reactors are used in various applications including drive systems for hybrid vehicles and electric vehicles. For example, a reactor in which a coil is wound around a resin bobbin disposed around a core is often used as a reactor used in an in-vehicle booster circuit.

  A magnetically coupled reactor is known as this type of reactor. The magnetically coupled reactor makes it difficult to saturate the core by generating magnetic flux in the canceling direction, and enables miniaturization by suppressing ripples using leakage inductance. As shown in FIG. 17, the magnetically coupled reactor includes an annular core 101 and a pair of coils 105 attached to each of the opposing leg portions of the annular core 101.

JP 2011-124267 A

  The magnetically coupled reactor has the advantages as described above, but generates magnetic flux in the canceling direction. Therefore, there is no path for the magnetic flux in the coil 105, and the magnetic flux generated from the two coils repels each other and returns to the coil again. The magnetic flux returning to the coil increases eddy current loss and heats the coil.

  The present invention has been proposed in order to solve the above-described problems of the prior art, and provides a reactor in which heat generation in a coil is reduced.

  In order to achieve the above object, a reactor according to the present invention includes an annular core including a pair of leg portions and a pair of yoke portions, and a plurality of coils that are concentrically wound around the leg portions along the axial direction. And a plurality of magnetic shields that are paired with the coil and installed so as to cover the coil, and generate magnetic fluxes from the plurality of coils in directions in which the generated magnetic fluxes repel each other, The plurality of magnetic shields are provided between each of the magnetic shields and between the magnetic shield and the yoke portion, and between the coil and a region where magnetic flux generated from the coil repels. It is characterized by being.

  ADVANTAGE OF THE INVENTION According to this invention, the reactor which suppressed the heat_generation | fever of a coil can be provided in a reactor.

It is a perspective view which shows the whole structure of the reactor which concerns on 1st Embodiment. It is a disassembled perspective view which shows the structure of the annular core which concerns on 1st Embodiment. It is a top view which shows the structure of the cyclic | annular core which concerns on 1st Embodiment. It is a side view of the annular core of a 1st embodiment. It is a top view which shows the mode of the magnetic flux which generate | occur | produces from the conventional reactor. It is a top view which shows the mode of the magnetic flux which generate | occur | produces from the reactor of 1st Embodiment. It is a plot figure which shows the mode of the magnetic flux which generate | occur | produces from the reactor of 1st Embodiment. It is a graph which shows the loss in the reactor of 1st Embodiment. It is a graph which shows the superimposition characteristic of the inductance current in the reactor of 1st Embodiment. It is a graph which shows the magnetic coupling coefficient in the reactor of 1st Embodiment. It is a graph which shows the ripple current waveform in each coil in the reactor of 1st Embodiment. It is a top view which shows the other structure of 1st Embodiment. It is a top view which shows the structure of the modifications 1 and 2 of the reactor of 1st Embodiment. It is a top view which shows the structure of the annular core which concerns on 2nd Embodiment. It is a plot figure which shows the mode of the magnetic flux which generate | occur | produces from the reactor of 2nd Embodiment. It is a graph which shows the loss in the reactor of 2nd Embodiment. It is a top view which shows the structure of the annular core in the conventional reactor.

  Hereinafter, a reactor according to an embodiment of the present invention will be described with reference to the drawings.

[1. First Embodiment]
In the reactor according to the present embodiment, a magnetic shield for preventing the repelled leakage magnetic flux from returning to the coil is disposed between the region where the magnetic flux generated from the coil repels and the coil.

[1-1. Schematic configuration]
The magnetic shield structure of the reactor of this embodiment is demonstrated using FIG. FIG. 1 is a perspective view showing the overall configuration of the reactor according to the present embodiment, and FIG. 2 is an exploded perspective view thereof. In the present specification, to describe the configuration of each member, the z-axis direction shown in FIG. 1 is referred to as the “upper” side, and the opposite direction is referred to as the “lower” side. “Lower” is also referred to as “bottom”. The z-axis direction is the vertical direction of the reactor and the height direction of the reactor.

  The reactor 1 is an electromagnetic component that converts electric energy into magnetic energy and stores and discharges it, and is used for voltage step-up / step-down and the like. The reactor according to the present embodiment is a large-capacity reactor used in, for example, a drive system for a hybrid vehicle or an electric vehicle. The reactor is a main component of the booster circuit mounted on these automobiles. In the present embodiment, the number of reactor main bodies 10 is one, but it may be two or more.

  The reactor 1 includes an annular core 3, coils 4a and 4b, and a magnetic shield 5. The annular core 3 includes a magnetic material such as a dust core, a ferrite core, or a laminated steel plate. Coils 4a and 4b are attached to a part of the outer periphery of the annular core 3, and the magnetic shield 5 is disposed so as to cover each of the coils 4a and 4b.

(Annular core)
The annular core 3 is an annular core having no end. The annular core 3 is made of a magnetic material such as a dust core, a ferrite core, or a laminated steel plate. Here, the annular core 3 is a dust core. In the annular core 3, a magnetic flux is generated by the legs 7a and 7b around which the coils 4a and 4b are wound. On the other hand, the U-shaped connecting portions around which the coils 4a and 4b are not wound are yoke portions 8a and 8b through which magnetic flux generated in the leg portions 7a and 7b passes.

  The annular core 3 includes a pair of parallel leg portions 7 a and 7 b and a pair of yoke portions 8. For convenience, the rear leg in FIG. 1 is referred to as a leg 7a, and the front leg is referred to as a leg 7b. The left yoke portion in FIG. 1 is referred to as a yoke portion 8a and the right yoke portion 8b.

  The leg portions 7a and 7b are portions around which the coils 4a and 4b are wound. The leg portion 7a and the leg portion 7b have the same shape, and the leg portions 7a and 7b are columnar members having a certain length. The cross-sectional shape of the leg portions 7a and 7b may be arbitrary, for example, a rectangle with rounded corners. The yoke portions 8a and 8b serve as a connecting portion that connects the leg portion 7a and the leg portion 7b. The yoke portion 8a and the yoke portion 8b have the same shape. The yoke part and the leg part may be a continuous member formed integrally.

  The annular core 3 may be formed by combining a plurality of core members. As shown in FIG. 2, the annular core 2 of the present embodiment is formed of core members 3a and 3b, and the core members 3a and 3b have bonding surfaces 3c for bonding the respective members, and bonding the bonding surfaces 3c to each other. They are connected so as to form a ring. In the present embodiment, the core members 3a and 3b are U-shaped core members, and two U-shaped core members are combined to form an annular core. Hereinafter, the core members 3a and 3b are referred to as U-shaped cores 3a and 3b. In this case, the leg portion 7a is formed by combining a part of the two U-shaped cores 3a and 3b. The leg portion 7a is a combination of a leg portion 71a that is a part of the U-shaped core 3a and a leg portion 72a that is a part of the U-shaped core 3b. Similarly, the leg portion 7b includes a leg portion 71b and a leg portion 72b.

  An adhesive is applied to the bonding surface 3c of the U-shaped cores 3a and 3b to bond the U-shaped cores 3a and 3b. The adhesive is not particularly limited, but a thermosetting adhesive can be used. Examples of the adhesive include an epoxy adhesive, a silicone adhesive, and an acrylic adhesive. Among those exemplified, an epoxy adhesive is preferable because of its high strength. In this embodiment, no spacer is provided between the U-shaped cores 3a and 3b, but a spacer may be interposed between the U-shaped cores 3a and 3b.

(coil)
The coils 4a and 4b are coils having a predetermined coil length and are obtained by winding a conductive wire having an insulating coating for several turns. Coil 4a, 4b is a pair of right and left in those structures, and is wound by the parallel leg parts 7a and 7b. The coils 4 a and 4 b are mounted so as to surround the periphery of the leg portion of the annular core 3. The winding direction of the coil 4a and the coil 4b is the same direction. The coils 4a and 4b realize the coil length by being wound a plurality of turns along the length direction of the legs. In each of the coils 4a and 4b, if the axis extending in the length direction of the coil, in other words, the length direction of the leg portion is used as the winding axis, the winding axes of the coils 4a and 4b are parallel to each other. The coils 4a and 4b are edgewise coils wound with a flat wire. However, the wire material and winding method of the coils 4a and 4b are not limited to the edgewise coil of a rectangular wire, and may be other forms.

  The coils 4a and 4b are magnetically a pair of left and right. In other words, the magnetic flux generated in the coil 4a and the magnetic flux generated in the coil 4b repel each other. The direction of the magnetic flux generated from the coils 4a and 4b wound in the same direction varies depending on the direction of the current. By controlling the direction of the current applied to the coils 4a and 4b, the magnetic flux generated in the coil 4a and the magnetic flux generated in the coil 4b are repelled from each other.

  The coils 4a and 4b are each connected to an individual power source (not shown). The ends of the coils 4a and 4b are drawn out of the reactor, and are wired and connected to an external device such as an external power source. From the external power supply, a current is generated to the coils 4a and 4b so as to generate magnetic fluxes repelling each coil. That is, currents in the same direction are supplied to the coils 4a and 4b. When a current flows through the coils 4a and 4b, a magnetic flux penetrating the coils 4a and 4b is generated. Magnetic fluxes generated from the coils 4a and 4b repel each other on the yoke portion 8a or the yoke portion 8b. That is, the magnetic fluxes generated from the coils 4a and 4b constituting the reactor 1 repel each other. The reactor 1 of the present embodiment can be rephrased as a magnetic repulsion type reactor that forms a so-called repulsive magnetic circuit.

  The position of the region α moves depending on the relationship of the magnetic flux density in the coils 4a and 4b. However, when the magnetic flux density in the coils 4a and 4b is the same, the position of the region α is the yoke portion that is equidistant from the coils 4a and 4b. It becomes a portion 8a. In that case, in FIG. 3, it discharges | releases in the outer peripheral direction of the yoke part 8a, and an inner peripheral direction. Among these, the magnetic flux emitted in the inner circumferential direction extends in the directions of the coils 4a and 4b.

(Magnetic shield)
As shown in FIG. 2, the annular core is provided with four magnetic shields 61a, 61b, 62a and 62b. The magnetic shield serves as a path for the magnetic flux emitted from the region α toward the inner circumferential direction and suppresses returning to the coils 4a and 4b. The magnetic shields 61a, 61b, 62a and 62b are plate-like members. The magnetic shield is a magnetic material. By using the magnetic shield as a magnetic material, it is possible to suppress the generation of eddy currents when magnetic flux flows.

  The shape of the magnetic shields 61a, 61b, 62a, and 62b may be any shape as long as it is a shape that blocks the magnetic flux emitted from the region α toward the inner circumferential direction. For example, a plate-like member having a rectangular plane arranged so as to protrude around the leg portion may be used. The magnetic shields 61a and 62a are erected in the vertical direction from the legs.

  The magnetic shields 61a, 61b, 62a and 62b are arranged so as to cover the coils 4a and 4b. Two magnetic shields are arranged for one coil. Covering the coil can also be described as sandwiching. For example, the magnetic shields 61a and 62a are disposed on the coil 4a in the winding axis direction and at both ends of the coil 4a. From the viewpoint of the coil 4a, a magnetic shield 61a is disposed on one side above the extension line in the winding axis direction of the coil 4a, and a magnetic shield 62a is disposed on the other side on the extension line in the winding axis direction of the coil 4a. The same applies to the coils 61b and 62b arranged in the coil 4b. Each magnetic shield is arranged with a predetermined gap from other magnetic shields.

  A coil is wound between the magnetic shields 61a and 62a. The coils 4a and 4b and the magnetic shields 61a and 62a are arranged with a predetermined gap therebetween. In the case where the coil 4a is an edgewise coil, the plate-like coil is wound so as to be perpendicular to the leg portion. The locations where the magnetic shields 61a and 62a are erected are locations away from the end of the coil, and the magnetic shields 61a and 62a are arranged at a predetermined distance from the coil 4a. Therefore, a predetermined gap is formed between the coil and the magnetic shields 61a and 62a.

  FIG. 3 is a plan view of the reactor U-shaped core 3a according to the present embodiment as viewed from above, and FIG. 4 is a side view of the U-shaped core as viewed from the side of the reactor according to the present embodiment. As shown in FIG. 3, two U-shaped cores 3a are provided with two magnetic shields 61a and 61b. The shape of the U-shaped core 3a is such that the legs 71a and 71b penetrate through the central portions of the plate-like magnetic shields 61a and 61b. That is, the magnetic shields 61a and 61b are in contact with the leg portions 71a and 71b at the central portion. A yoke portion 8a exists in the thickness direction of the magnetic shields 61a and 61b. In the thickness direction, a gap of length D1 is provided between the magnetic shields 61a and 61b and the yoke portion 8a. This gap is defined as a first gap. A gap with a length D2 is provided between the magnetic shields 61a and 61b. This gap is the second gap.

  Moreover, as shown in FIG. 4, the shape of the magnetic shields 61a and 61b is a rectangle consisting of four sides. The lengths of the four sides are longer than the diameters of the coils 4a and 4b wound around the leg portions 71a and 71b. When the U-shaped core 3a and the magnetic shields 61a and 61b are made of the same material, the magnetic shields 61a and 61b may be formed integrally with the U-shaped core 3a. Separately, magnetic shields 61a and 61b provided with holes for fitting the U-shaped core 3a in the center are prepared separately from the U-shaped core 3a, and the magnetic shields 61a and 61b are attached to the U-shaped core 3a. It may be formed by inserting it through.

[1-2. Action]
When a current is passed through the coils 4a and 4b of the reactor 1 having the above-described configuration and a magnetic flux is generated, the magnetic flux is generated from each of the coils 4a and 4b. The generated magnetic flux collides, and a part of the collided magnetic flux leaks in the direction of the coils 4a and 4b. The magnetic flux returning to the coils 4a and 4b is defined as a leakage magnetic flux. The leakage flux returns to the flow of magnetic flux generated from the coils 4a and 4b via the inside of the magnetic shield.

  FIG. 5 is a schematic diagram illustrating a state of magnetic flux generated in a conventional reactor, and FIG. 6 is a diagram illustrating a state of magnetic flux generated in the reactor 1. In FIG. 5, attention is paid only to the flow of the two-dimensional magnetic flux in the plane including the axes of the coils 4a and 4b among the magnetic fluxes generated in the coils 4a and 4b. As shown in FIG. 5, magnetic flux is generated in the direction of arrow A from the coils 4a and 4b, respectively. The generated magnetic flux repels in the region α, and a part of the magnetic flux collides with the coil as a leakage flux.

  In FIG. 6, attention is paid only to the flow of the two-dimensional magnetic flux in the plane including the axes of the coils 4a and 4b among the magnetic fluxes generated in the coils 4a and 4b. As shown in FIG. 6, magnetic fluxes are generated in the direction of arrow A from the coils 4a and 4b, respectively. A part passes through the magnetic shields 61a and 61b and extends in the outer circumferential direction. And it discharge | releases outside from the magnetic shield outer periphery. The magnetic flux generated in the coils 4a and 4b repels in the region α, and a part of the magnetic flux flows into the leakage magnetic flux and the magnetic shields 61a and 61b. The magnetic flux flowing into the magnetic shields 61a and 61b flows to the leg portions 71a and 71b, and returns to the flow of magnetic flux generated from the coils 4a and 4b. Thus, by installing the magnetic shields 61a and 61b between the region 4a where the magnetic flux generated from the coil repels and the coil 4a, the leakage magnetic flux can be prevented from returning to the coils 4a and 4b. .

  FIG. 7 is a plan view showing the flow of magnetic flux in the reactor of the present embodiment. FIG. 7 is a vector plot that visualizes the flow of magnetic flux in the reactor. As shown in FIG. 7, there is almost no arrow indicating the magnetic flux in the region α where the magnetic fluxes generated from the two coils 4a and 4b repel each other. There is an arrow indicating a slight magnetic flux, but this arrow indicates a repulsive magnetic flux and becomes an arrow extending in the vertical direction.

  On the other hand, in the region β located on the inner peripheral side of the magnetic shields 61a and 61b, part of the magnetic flux repelled in the region α flows into the magnetic shields 61a and 61b. The magnetic flux that has flowed into the magnetic shields 61a and 61b in the region β moves in the magnetic shield. And magnetic flux is discharge | released outside in the area | region (gamma) located in the outer peripheral side of the magnetic shields 61a and 61b.

[1-3. effect]
(1) The reactor of the present embodiment includes U-shaped cores 3a and 3b including a pair of leg portions 71a, 71b, 72a and 72b and a pair of yoke portions 8a and 8b, and leg portions 71a, 71b, 72a and 72b. Coil 4a, 4b wound concentrically along the axial direction, and magnetic shields 61a, 61b installed so as to cover the coils 4a, 4b. The coils 4a and 4b are wound around the legs 71a, 71b, 72a and 72b, and the winding is wound in such a direction that the magnetic fluxes generated from the coils 4a and 4b repel each other. The magnetic shields 61a, 61b, 62a, and 62bb are installed between the region α where the magnetic flux generated from the coil repels and the coils 4a and 4b.

  Further, in the present embodiment, the magnetic shields 61a, 61b, 62a, 62b are in contact with the leg portions and provided with a first gap between the yoke portions. When the magnetic shields 61a, 61b, 62a, 62b are in contact with the yoke part, the magnetic shields 61a, 61b, 62a, 62b and the yoke part are magnetically integrated, and the repelled and leaked magnetic flux is reflected by the magnetic shield 61a, It passes through 61b, 62a and 62b and flows into coils 4a and 4b. On the other hand, by providing a gap between the magnetic flux part and the yoke part as in the present embodiment, the magnetic flux that has flowed into the magnetic shields 61a, 61b, 62a, 62b passes through the magnetic shields 61a, 61b, 62a, 62b. It can prevent moving and returning to the coils 4a and 4b. Thereby, by providing the magnetic shields 61a, 61b, 62a, and 62b, it is possible to prevent leakage current from flowing into the coils 4a and 4b, and it is possible to provide a reactor that suppresses heat generation.

  The annular core 3 is a U-shaped core composed of a plurality of leg portions and one yoke portion. This U-shaped core has a plurality of magnetic shields 61a, 61b, 62a, 62b, and a second gap is provided between the magnetic shields 61a, 61b and between the magnetic shields 62a, 62b. Thereby, it functions as a magnetic shield with respect to each coil 4a, 4b because the magnetic shield is separated. When the magnetic shields 61a and 61b covering the different coils 4a and 4b and the magnetic shields 62a and 62b are in contact with each other, the leakage flux passes through the magnetic shield without being a shield against the leakage flux, and the coils 4a and 4b. Will flow into. In other words, by providing gaps between the magnetic shields 61a and 61b installed in the coils 4a and 4b and between the magnetic shields 62a and 62b, it is possible to provide a reactor that functions as a magnetic shield and suppresses heat generation. it can.

(Reduction of leakage magnetic flux flowing into the coil)
Table 1 compares the loss in the number of turns of the coils 4a and 4b with and without the magnetic shields 61a, 61b, 62a, and 62b. FIG. 8 shows the magnetic shield 61a based on Table 1. , 61b, 62a, and 62b. In Table 1 and FIG. 8, the number of turns is the number of turns, and 1 turn indicates the first turn from the end.

  As shown in FIG. 8 and Table 1, in the first turn, the loss without the magnetic shield is 26.9 (W), and the loss with the magnetic shields 61a, 61b, 62a, and 62b is 18.2 (W). The loss decreases as the number of turns progresses to 10 for both the absence of the magnetic shield and the presence of the magnetic shields 61a, 61b, 62a, and 62b. On the other hand, when the number of turns exceeds 15, the loss increases with no magnetic shield and with the magnetic shields 61a, 61b, 62a, 62b. In the 25th turn, the loss without the magnetic shield is 26.9 (W), and the loss with the magnetic shields 61a, 61b, 62a, and 62b is 18.8 (W). From the above, regardless of the presence or absence of the magnetic shield, the influence of the leakage magnetic flux is large at the end of the coil. And by providing the magnetic shields 61a, 61b, 62a, 62b, eddy current loss due to leakage magnetic flux can be reduced. Thereby, the reactor which suppressed the heat_generation | fever resulting from an eddy current loss can be provided.

(2) In the present embodiment, the magnetic shields 61a, 61b, 62a and 62b are magnetic bodies. By using the magnetic shield as a magnetic material, it is possible to provide a reactor that suppresses heat generation due to ripple current. FIG. 9 is a diagram illustrating the inductance superposition characteristics in the reactor when there is a magnetic shield and when there is no magnetic shield. FIG. 9 shows the magnitude of the inductance with respect to the current. As shown in FIG. 9, by providing the magnetic shields 61a, 61b, 62a, 62b, the effect of increasing the self-inductance L can be obtained. On the other hand, the mutual inductance is also increased, but the amount of increase is small. FIG. 10 is a diagram illustrating the coupling coefficient in the reactor when the magnetic shields 61a, 61b, 62a, and 62bb are present and when there is no magnetic shield. FIG. 10 shows the coupling coefficient with respect to the current. The coupling coefficient is calculated from the following equation (2) from the self-inductance and the mutual inductance.

[Formula (2)]
Magnetic coupling coefficient = mutual inductance M / self inductance L

  In the reactor provided with the magnetic shields 61a, 61b, 62a, 62b, the self-inductance L increases. Therefore, when the magnetic coupling coefficient is calculated, the self-inductance L located in the denominator increases, so that the magnetic coupling coefficient when the magnetic shields 61a, 61b, 62a, and 62b are provided becomes low.

  11A shows the ripple current waveform on the coil 4a side, and FIG. 11B shows the ripple current waveform on the coil 4b side. FIGS. 11A and 11B show waveforms of current (A) with respect to time (s). As shown in FIGS. 11 (a) and 11 (b), the reactor provided with the magnetic shields 61a, 61b, 62a, 62b on both the coils 4a, 4b side has a maximum current value as compared with the case where the magnetic shield is not provided. The difference between the value and the minimum value is reduced. In other words, the ripple current can be kept low. That is, by providing the magnetic shields 61a, 61b, 62a, and 62b, the magnetic coupling coefficient can be kept low, and the ripple current during the magnetic coupling operation is reduced. The ripple current is related to the heat generation of the coil, and when the ripple current increases, the heat generation amount of the coil increases. Therefore, by providing the magnetic shields 61a, 61b, 62a, and 62b, it is possible to provide a reactor that suppresses heat generation due to the ripple current by suppressing the ripple current.

  As described above, in the present embodiment, the annular core 3 and the four magnetic shields 61a, 61b, 62a, and 62b are magnetic bodies. When the annular core 3 and the magnetic shields 61a, 61b, 62a and 62b are integrally molded, the same material may be used. By using the same material for the annular core 3 and the magnetic shields 61a, 61b, 62a and 62b, the annular core 3 and the magnetic shields 61a, 61b, 62a and 62b can be integrally formed. Therefore, it is possible to reduce the number of parts, thereby improving the assemblability. On the other hand, the annular core 3 and the magnetic shields 61a, 61b, 62a and 62b can be made of magnetic materials of different materials. For example, in the case where separate magnetic shields 61a and 61b are prepared separately from the U-shaped core 3a and the magnetic shields 61a and 61b are inserted into the U-shaped core 3a and passed therethrough, etc. , Each need not be the same material. Therefore, it is possible to select a material suitable for the annular core 3 and a material suitable for the magnetic shields 61a, 61b, 62a and 62b from the viewpoint of processing and magnetic characteristics. Thereby, while preventing leakage current from flowing into the coils 4a and 4b, it is possible to provide a reactor excellent in workability and a reactor in which current flow is prevented and heat generation is suppressed.

(3) In the present embodiment, the magnetic shields 61a, 61b, 62a and 62b are made of a magnetic material. However, by providing the magnetic shields 61a, 61b, 62a and 62b, leakage current can be prevented from flowing into the coils 4a and 4b. If possible, the magnetic shields 61a, 61b, 62a and 62b may not be magnetic. For example, a metal having good conductivity such as aluminum or copper can be used.

(4) In the present embodiment, the magnetic shields 61a, 61b, 62a, 62b are installed at both ends of the coil. The magnetic shields 61a, 61b, 62a, and 62b are provided to prevent the magnetic flux generated from the coil from repelling and leaking from flowing into the coil. When the leakage magnetic flux flows into the coil, there is a high possibility that it passes through the vicinity of both ends of the coils 4a and 4b. Therefore, by providing the magnetic shields 61a, 61b, 62a, 62b where the leakage magnetic flux flowing into the coils 4a, 4b passes, it is possible to efficiently prevent the leakage magnetic flux from flowing into the coils 4a, 4b. . Thereby, reduction of the eddy current loss by leakage magnetic flux and reduction of ripple current can be aimed at, and the reactor which suppressed heat_generation | fever can be provided.

  In this embodiment, the magnetic shields 61a, 61b, 62a, 62b are installed at both ends of the coils 4a, 4b. However, if the magnetic shields 61a, 61b, 62a, 62b are installed so as to cover the coils, the magnetic shields 61a, 61b, 62a, 62b may be installed at other than both ends of the coil. FIGS. 12A and 12B are diagrams showing the configurations of the first and second modifications of the present embodiment. In FIG. 12A, magnetic shields 61a, 61b, 62a, 62b are installed so as to cover the coils 4a, 4b. In FIG. 12A, ball-shaped magnetic shields 61a, 61b, 62a, 62b are installed above and below one coil. In FIG. 12A, magnetic shields 61a, 61b, 62a, 62b having L-shaped cross sections are provided above and below the coils 4a, 4b. At this time, a certain gap is provided between the upper and lower magnetic shields 61a, 61b, 62a, 62b. Further, the magnetic shields 61a, 61b, 62a, 62b are in contact with the legs, but are not in contact with the coils 4a, 4b and the yoke.

  Also in FIG. 12B, the magnetic shields 61a, 61b, 62a, 62b are installed so as to cover the coils 4a, 4b. In FIG. 12B, disk-shaped magnetic shields 61a, 61b, 62a, 62b are installed above and below one coil 4a, 4b. In the disk-shaped magnetic shields 61a, 61b, 62a, and 62b, the radius of the outer circle is longer than the radius of the coil. Further, the disk-shaped magnetic shields 61a, 61b, 62a, and 62b may be connected to the legs by magnetic members (not shown). By connecting the leg portions and the magnetic shields 61a, 61b, 62a, 62b by magnetic members, magnetic flux can easily flow between the magnetic shields 61a, 61b, 62a, 62b and the leg portions.

  In the embodiment, the magnetic shields 61a, 61b, 62a, and 62b are formed integrally with the U-shaped core, or are formed by fitting the separate magnetic shields 61a, 61b, 62a, and 62b into the legs. The magnetic shields 61a, 61b, 62a, 62b may be installed so as to be covered with the coils 4a, 4b by a method. For example, when the coils 4a and 4b are wound around the legs and then molded with resin together with the coils 4a and 4b, they are molded with resin together with the magnetic shields 61a, 61b, 62a and 62b positioned with respect to the legs. You can also. That is, by providing the magnetic shields 61a, 61b, 62a, 62b so as to be covered with the coils 4a, 4b, it is possible to prevent leakage current from flowing into the coils 4a, 4b, and to provide a reactor that suppresses heat generation. can do.

(5) The legs of this embodiment are installed in parallel, and the magnetic shields 61a, 61b, 62a, 62b provided on the legs are rectangular. When the magnetic shields 61a, 61b, 62a, 62b are larger than the size of the coils 4a, 4b, leakage flux can be efficiently prevented from flowing into the coils 4a, 4b. Further, the smaller the gap between the magnetic shields 61a, 61b, 62a, 62b between the coil 4a and the coil 4b, the more efficiently the leakage magnetic flux can be shielded. In a U-shaped core with parallel legs, the gap between the magnetic shields can be efficiently reduced by making the shape of the magnetic shields installed in the coils 4a and 4b rectangular.

[First Modification]
In the first embodiment, the magnetic shields 61a, 61b, 62a, and 62b are formed integrally with the U-shaped core, or the separate magnetic shields 61a, 61b, 62a, and 62b are fitted into the legs. In this modification, the mounting method of the magnetic shield is changed. In this modification, a cylindrical bobbin 9 around which a coil is wound is attached to the leg portion. Magnetic shields are provided at both ends of the bobbin 9, respectively.

  FIG. 13A is a cross-sectional view showing the configuration of this modification. As shown to Fig.13 (a), the bobbin 9 is mounted | worn with a leg part along a leg part outer periphery. The bobbin 9 has a cylindrical shape, and the inner shape thereof coincides with the shape of the leg portion. The bobbin is made of a material such as resin, magnetic material or metal.

  Therefore, when creating the reactor, an unbonded U-shaped leg is attached to the bobbin 9, and another U-shaped core is bonded in that state. Thus, the coils 4a and 4b are not directly wound around the legs, but are wound around the bobbins 9, so that the magnetic shields 61a, 61b, 62a and 62b are connected to the legs and arranged. Therefore, it is not necessary to prepare a separate process. By using the bobbin 9 provided with the magnetic shield, it is not necessary to assemble the magnetic shield separately, so that the assemblability is improved. Moreover, when arrange | positioning a magnetic shield in the both ends of the bobbin 9, the bobbin 9 and a magnetic shield are good also as a continuous same member.

[Second Modification]
In the reactor of the second modified example, the periphery of the core member is covered with the resin member 5 as shown in FIG. As a method of covering the periphery of the core member 3 with the resin member 5, molding is performed with resin. At this time, the magnetic shields 61a, 61b, 62a, 62b positioned with respect to the annular core are molded with resin. In other words, the magnetic shields 61a, 61b, 62a, 62b are buried in the resin member 5, and the relative positions of the magnetic shields 61a, 61b, 62a, 62b and the annular core are fixed by the resin member. Therefore, it is not necessary to assemble the magnetic shields 61a, 61b, 62a, 62b separately, so that assemblability is improved.

[2. Second Embodiment]
A second embodiment will be described. In the second embodiment, the coils 10a and 10b are arranged in series on one side of the annular core. Also in this embodiment, magnetic shields 11a and 11b for preventing the repelled magnetic flux from returning to the coils 10a and 10b are arranged between the region α where the magnetic flux generated from the coils 10a and 10b repels and the coils 10a and 10b. Thus, it is possible to achieve the same effect as in the above embodiment.

[2-1. Constitution]
FIG. 14 is a cross-sectional view showing the configuration of the second embodiment. In addition, the same code | symbol is attached | subjected to the structure same as 1st Embodiment, and the overlapping description is abbreviate | omitted.

(Annular core)
The core member of this embodiment is the two U-shaped cores 3a and 3b. The coils 10a and 10b are wound around the leg portions 71a and 72a of the U-shaped cores 3a and 3b, and no coil is wound around the other leg portions 71b and 72b. And the core member is formed by adhere | attaching the leg parts 71a and 72a of the side by which the coils 10a and 10b were wound. In other words, the two coils 10a and 10b are attached to the leg portions 71a and 72a constituting one leg portion of the annular core.

  The coils 10a and 10b are a pair of left and right coils, and the winding direction of the coils 10a and 10b is opposite. When power is supplied from an external power source to the coils 10a and 10b whose winding directions are opposite to each other, and a current in the same direction flows through each of the coils 10a and 10b, the direction indicated by the arrow B in the figure is from the coils 10a and 10b. That is, a magnetic flux is generated in a direction toward the opposing coil.

(Magnetic shield)
As shown in FIG. 14, two magnetic shields 11a and 11b are provided on one leg of the U-shaped core. One magnetic shield 11a is located at the end of the coil 4a, and one magnetic shield 11b is located at the end of the coil 4b. The shape of the magnetic shields 11a and 11b of this embodiment may be a shape that covers the end of the coil.

[2-2. Action]
In the reactor having the above-described configuration, the direction of the magnetic flux generated from the two coils 10a and 10b is reversed. Therefore, when a current is passed through the coils 10a and 10b and a magnetic flux is generated, the magnetic fluxes generated from the coils 10a and 10b collide with each other.

  FIG. 15 is a diagram illustrating a state of magnetic flux generated in the reactor 1. As shown in FIG. 15, magnetic flux is generated in the direction of arrow B from the coils 10a and 10b, respectively. The magnetic flux generated in the coil 10a repels in the region α. Then, it passes through the magnetic shield 11a and flows into the legs where the coil 10a is not wound. And it returns in the coil 10a via the yoke part 8a. As described above, the magnetic shields 11a and 11b act as paths for the magnetic flux by installing the magnetic shields 11a and 11b between the regions where the magnetic fluxes generated from the coils 10a and 10b repel each other and the coils 10a and 10b. . Thereby, it is possible to prevent the leakage magnetic flux from returning to the coils 10a and 10b.

[2-3. effect]
(Reduction of leakage magnetic flux flowing into the coil)
Table 2 is a table comparing the loss in the number of turns 10a and 10b with and without the magnetic shields 11a and 11b. FIG. 16 shows the presence or absence of the magnetic shields 11a and 11b based on Table 2. It is the figure which showed the different loss. In Table 2 and FIG. 16, the number of turns is the number of turns, and 1 turn indicates the first turn from the end. In this embodiment, a magnetic shield is provided on the 10-turn side.

  As shown in FIG. 16 and Table 2, the loss increases as the number of turns progresses from 3 turns to 10 turns with no magnetic shield and with magnetic shields 11a and 11b. In the 10th turn, the loss without the magnetic shield is 6.6 (W), and the loss with the magnetic shields 11a and 11b is 4.4 (W). From the above, regardless of the presence or absence of the magnetic shields 11a and 11b, the influence of the leakage magnetic flux is large at the ends of the coils 10a and 10b. And by providing the magnetic shields 11a and 11b, eddy current loss due to leakage magnetic flux can be reduced. Thereby, also in this embodiment, the reactor which suppressed the heat_generation | fever resulting from an eddy current loss can be provided.

[3. Other Embodiments]
In the present specification, a plurality of embodiments according to the present invention have been described. However, these embodiments are presented as examples and are not intended to limit the scope of the invention. Specifically, various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the invention described in the claims and equivalents thereof as well as included in the scope and gist of the invention.

  For example, in the first embodiment, in order to repel the magnetic flux generated in the coil 4a and the magnetic flux generated in the coil 4b, currents in the same direction are supplied to the coils 4a and 4b wound in the same direction. did. However, if the magnetic flux generated in the coil 4a and the magnetic flux generated in the coil 4b repel each other, the winding direction of the coil and the direction of the current may be arbitrary. For example, the coil 4a and the coil 4b may be wound in opposite directions, and a current in the opposite direction may be passed through the coils 4a and 4b.

DESCRIPTION OF SYMBOLS 1 ... Reactor 3 ... Ring core 3a, 3b ... U-shaped core 3c ... Adhesive layer 4a, 4b ... Coil 5 ... Resin member 7a, 7b ... Leg part 8a, 8b ... Yoke part 9 ... Bobbin 10a, 10b ... Coil 10 ... Reactor body 11a, 11b ... Magnetic shield 61a, 61b ... Magnetic shield 62a, 62b ... Magnetic shield 62b ... Magnetic shield 71a, 71b ... Leg 101 ... Annular core 105 ... Coil

Claims (10)

An annular core comprising a pair of legs, a pair of yokes, and a plurality of coils wound concentrically around the legs along the axial direction;
A plurality of magnetic shields paired with the coil and installed to cover the coil;
With
Each of the plurality of coils generates a magnetic flux in a direction in which the generated magnetic flux repels,
The plurality of magnetic shields have a gap between each of the magnetic shields, and between the magnetic shield and the yoke portion, and between a region where the magnetic flux generated from the coil repels and the coil. A reactor characterized by being installed. Two magnetic shields are installed for one coil,
The reactor according to claim 1, wherein the magnetic shield is installed at both ends of the coil.   The reactor according to claim 1, wherein the magnetic shield is a magnetic body.   The reactor according to claim 1, wherein the magnetic shield is installed so as to contact the leg portion.   The reactor according to claim 4, wherein the magnetic shield and the annular core are a series of identical members. It further includes a cylindrical bobbin attached to the leg and around which the coil is wound,
The reactor according to any one of claims 1 to 3, wherein the reactor is installed so that the magnetic shields are in contact with both ends of the bobbin.   The reactor according to claim 6, wherein the bobbin and the magnetic shield are a series of identical members. A resin member covering the periphery of the annular core;
The reactor according to any one of claims 1 to 3, wherein the magnetic shield is fixed in a relative position with the annular core by the resin member.   The reactor according to any one of claims 1 to 8, wherein the leg portions are parallel to each other. The reactor according to any one of claims 1 to 9, wherein the magnetic shield has a rectangular shape.