Reactor, converter, and power conversion device

Abstract

A reactor comprises a coil, a magnetic core, and a molded resin portion. The magnetic core comprises a first core piece, a second core piece, and a gap portion. The first core piece and the second core piece are combined in a first direction along an axis of the coil. The gap portion is provided between the first core piece and the second core piece. The molded resin portion covers at least a part of the magnetic core. A first end face of a first middle core portion provided to the first core piece has a specific ridge portion or projecting piece portion.

Description

Reactor, Converter, and Power Conversion Device

[0001] This disclosure relates to a reactor, a converter, and a power conversion device. This application claims priority based on Japanese Patent Application No. 2024-206763 filed on November 27, 2024. All the descriptions described in the Japanese application are incorporated herein by reference.

[0002] The reactor disclosed in Patent Document 1 includes a coil, a magnetic core, and a molded resin part. The coil has a cylindrical winding part. The magnetic core has a first core piece and a second core piece combined in a first direction along the axis of the coil, and a gap part provided between the first core piece and the second core piece. The molded resin part covers the outer periphery of the combination of the coil and the magnetic core.

[0003] The shape of the first core piece is E-shaped. The first core piece has a first end core part, a first middle core part, a first side core part, and a second side core part. The first end core part and the first end face of the winding part face each other. The first middle core part has a part arranged inside the winding part. The first side core part and the second side core part are arranged facing each other so as to sandwich the first middle core part. The first side core part and the second side core part are arranged on the outer periphery of the winding part. The first core part is an integral molded body of the first end core part, the first middle core part, the first side core part, and the second side core part. The first end core part connects the first middle core part, the first side core part, and the second side core part.

[0004] The shape of the second core piece is T-shaped. The second core piece has a second end core part and a second middle core part. The second end core part and the second end face of the winding part face each other. The second middle core part has a part arranged inside the winding part. The second core piece is an integral molded body of the second end core part and the second middle core part.

[0005] A gap is provided between the first middle core section and the second middle core section. The gap is formed by filling a portion of the molded resin section. The first side core section and the second side core section are in contact with the second end core section.

[0006] Japanese Patent Publication No. 2023-47148

[0007] The reactor of this disclosure comprises a coil, a magnetic core having a first core piece and a second core piece combined in a first direction along the axis of the coil, and a gap portion provided between the first core piece and the second core piece, and a molded resin portion covering at least a part of the magnetic core. The first core piece has a plurality of parallel core pieces arranged in parallel along a second direction perpendicular to the first direction. One of the plurality of parallel core pieces is a first middle core piece disposed inside the coil, and one of the plurality of parallel core pieces is a first side core piece disposed outside the coil. The second core piece has a second middle core piece disposed inside the coil. The first middle core piece has a first surface and a second surface facing each other in a third direction perpendicular to both the first and second directions, and a first end surface connected to the first surface and the second surface and facing the second middle core piece. The second middle core piece has a second end surface facing the first middle core piece. The first end face has a non-contact portion spaced apart from the second end face, and two ridges or four projections projecting from the non-contact portion toward the second end face so as to be in contact with the second end face. The two ridges are spaced apart from each other in the second direction and extend from the first surface to the second surface. The four projections have two first projections spaced apart from each other in the second direction near the first surface, and two second projections spaced apart from each other in the second direction near the second surface. The gap portion has a middle gap portion provided between the non-contact portion and the second end face.

[0008] Figure 1 is a schematic perspective view showing the reactor of Embodiment 1. Figure 2 is a first schematic perspective view showing the reactor of Embodiment 1 in an disassembled state. Figure 3 is a second schematic perspective view showing the reactor of Embodiment 1 in an disassembled state. Figure 4 is a schematic perspective view showing the first end face of the first middle core portion provided in the reactor of Embodiment 1. Figure 5 is a schematic front view showing the first end face of the first middle core portion provided in the reactor of Embodiment 1. Figure 6 is a schematic top view showing the reactor of Embodiment 1. Figure 7 is a schematic bottom view showing the reactor of Embodiment 1. Figure 8 is a schematic front view showing the first end face of the first middle core portion provided in the reactor of Embodiment 2. Figure 9 is a schematic perspective view showing the first end face of the first middle core portion provided in the reactor of Embodiment 3. Figure 10 is a schematic front view showing the first end face of the first middle core portion provided in the reactor of Embodiment 3. Figure 11 is a schematic front view showing the first end face of the first middle core portion provided in the reactor of Embodiment 4. Figure 12 is a schematic top view showing the first core provided in the reactor of Embodiment 5. Figure 13 is a schematic bottom view showing the first core provided in the reactor of Embodiment 5. Figure 14 is a schematic configuration diagram showing the power supply system of a hybrid vehicle. Figure 15 is a circuit diagram showing an example of a power conversion device equipped with a converter.

[0009] A reactor that can easily obtain the desired inductance is desired.

[0010] One of the objectives of this disclosure is to provide a reactor that makes it easy to obtain a desired inductance.

[0011] The reactor of this disclosure makes it easy to obtain the desired inductance.

[0012] The inventors investigated the cause of the inability to obtain the desired inductance. As a result, they found that the following phenomenon is one of the causes. For example, when forming a molded resin part by combining an E-shaped core piece, a T-shaped core piece, and a coil, the resin constituting the molded resin part is filled from two directions: from the outside of the first end core part toward the inside of the winding part, and from the outside of the second end core part toward the inside of the winding part. A gap is provided between the first middle core part and the second middle core part, and the first side core part and the second side core part are in contact with the second end core part. In this case, the filling of the resin constituting the molded resin part from the above two directions may result in an uneven distance between the first middle core part and the second middle core part. This unevenness in distance leads to uneven spacing in the gap part, and consequently causes the inability to obtain the desired inductance. This disclosure is completed by finding the above cause. Embodiments of this disclosure will be listed and described first.

[0013] (1) A reactor according to one embodiment of the present disclosure comprises a coil, a magnetic core having a first core piece and a second core piece combined in a first direction along the axis of the coil, and a gap portion provided between the first core piece and the second core piece, and a molded resin portion covering at least a part of the magnetic core. The first core piece has a plurality of parallel core pieces arranged in parallel along a second direction perpendicular to the first direction. One of the plurality of parallel core pieces is a first middle core piece disposed inside the coil, and one of the plurality of parallel core pieces is a first side core piece disposed outside the coil. The second core piece has a second middle core piece disposed inside the coil. The first middle core piece has a first surface and a second surface facing each other in a third direction perpendicular to both the first and second directions, and a first end surface connected to the first surface and the second surface and facing the second middle core piece. The second middle core piece has a second end surface facing the first middle core piece. The first end face has a non-contact portion spaced apart from the second end face, and two ridges or four projections projecting from the non-contact portion toward the second end face so as to be in contact with the second end face. The two ridges are spaced apart from each other in the second direction and extend from the first surface to the second surface. The four projections have two first projections spaced apart from each other in the second direction near the first surface, and two second projections spaced apart from each other in the second direction near the second surface. The gap portion has a middle gap portion provided between the non-contact portion and the second end face.

[0014] The reactor described in (1) above has two protrusions or four projections, so that even if the resin constituting the molded resin part is filled from the two directions, the two protrusions or four projections will sufficiently support the second end face. As a result, the distance between the non-contact portion and the second end face tends to be uniform. That is, the spacing of the gap tends to be uniform. Therefore, the reactor described in (1) above makes it easy to obtain the desired inductance.

[0015] (2) In the reactor described in (1) above, the shape of the first core piece as viewed from the third direction may be E-shaped, and the shape of the second core piece as viewed from the third direction may be T-shaped. The first core piece has a first end core portion that is positioned opposite the first end face of the coil so as to connect the plurality of parallel core portions. The second core piece has a second end core portion that is positioned opposite the second end face of the coil so as to connect to the second middle core portion. The plurality of parallel core portions have a second side core portion that is positioned outside the coil on the opposite side of the first side core portion in the first middle core portion. The gap portion has a side gap portion provided between each of the first side core portion and the second side core portion and the second end core portion.

[0016] If the reactor described in (2) above does not have two protrusions and four projections, the spacing of the middle gap tends to be uneven, especially in the third direction. In contrast, the reactor described in (2) above, by having two protrusions or four projections, tends to have a uniform spacing of the middle gap in the third direction.

[0017] (3) In the reactor described in (2) above, the first core piece may have a low μ portion with a relatively low relative permeability and a high μ portion with a relatively high relative permeability. The low μ portion includes two corners, each composed of the first middle core portion and the first end core portion. The high μ portion includes a base end portion and a protruding portion. The base end portion extends along the second direction, straddling the axis of the first middle core portion, in the first end core portion. The protruding portion protrudes from the base end portion toward the second middle core portion.

[0018] Generally, magnetic flux tends to leak from near the junction between the first end core and the first middle core, i.e., from the two corners mentioned above. The reactor described in (3) above can control the flow of magnetic flux between the first middle core and the first end core. Specifically, the high-μ portion attracts the magnetic flux passing from the first middle core towards the first end core to the protruding portion and controls it to pass from the protruding portion towards the base end. The high-μ portion also controls the magnetic flux passing from the first end core towards the first middle core to guide it into the coil. Through these controls, the reactor described in (3) above can reduce leakage flux. In particular, the reactor described in (3) above can reduce leakage flux from the corners formed by the first middle core and the first end core. This reduction in leakage flux can reduce losses.

[0019] Although the reactor described in (3) above has a high μ region with relatively high relative permeability, the effect of having a high μ region on magnetic saturation is relatively small, so it can maintain high inductance.

[0020] (4) In the reactor described in (3) above, the base portion may be provided along the entire length of the first end core portion in the second direction.

[0021] The reactor described in (4) above is more effective at reducing leakage flux from each corner formed by the two side core sections and the first end core section compared to the case where the base end section is not provided along the entire length in the second direction of the first end core section.

[0022] (5) In the reactor described in (3) or (4) above, the relative permeability in the high μ portion may be 50 or more and 500 or less.

[0023] The reactor described in (5) above easily allows magnetic flux to pass through the high-μ region, thus making it easier to reduce leakage flux.

[0024] (6) In any of the reactors described in (3) to (5) above, the relative permeability in the low μ portion may be 5 or more and 50 or less.

[0025] The reactor described in (6) above is good at reducing leakage flux. Moreover, because the reactor described in (6) has a low-μ region where the relative permeability is in a specific low range, magnetic saturation that would occur with a high-μ region is less likely to occur, making it easier to maintain high inductance even in high-current operating environments.

[0026] (7) In any of the reactors described in (3) to (6) above, the relative permeability of the second core piece may be 50 or more and 500 or less.

[0027] The reactor described in (7) above makes it easy to obtain the desired inductance.

[0028] (8) In any of the reactors described in (3) to (7) above, the high μ portion may be made of a compacted soft magnetic powder.

[0029] Compared to molded bodies made of composite materials in which soft magnetic powder is dispersed in resin, powder-molded bodies make it easier to increase the content of soft magnetic powder and thus increase the relative permeability. Therefore, the reactor described in (8) above makes it easier to pass magnetic flux through the high μ region, thus making it easier to reduce leakage flux.

[0030] (9) In any of the reactors described in (3) to (8) above, the low μ portion may be made of a molded body of a composite material in which soft magnetic powder is dispersed in a resin.

[0031] Compared to compacted powder molded bodies, composite materials allow for easier adjustment of the soft magnetic powder content, making it easier to lower the relative permeability. Therefore, the reactor described in (8) above is less prone to magnetic saturation due to the presence of high-mu regions, making it easier to maintain high inductance even in high-current operating environments.

[0032] (10) In any of the reactors described in (1) to (9) above, the second core piece may be made of a compacted body of soft magnetic powder.

[0033] The reactor described in (10) above makes it easy to obtain the desired inductance.

[0034] (11) A converter according to one embodiment of the present disclosure comprises any of the reactors described in (1) to (10) above.

[0035] The above converter, equipped with the above reactor, offers superior performance.

[0036] (12) A power conversion device according to one embodiment of the present disclosure comprises the converter described in (11) above.

[0037] The above power conversion device has superior performance because it is equipped with the above converter.

[0038] The details of the embodiments of this disclosure will be described below with reference to the drawings. The same reference numerals in the drawings indicate the same parts. In each drawing, some parts of the configuration may be exaggerated or simplified for illustrative purposes. The dimensional ratios of the parts in the drawings may also differ from those of the actual components.

[0039] [Embodiment 1] <Reactor> The reactor 1 of Embodiment 1 will be described with reference to Figures 1 to 7. As shown in Figure 1, the reactor 1 comprises a coil 2, a magnetic core 3, and a molded resin portion 9. The magnetic core 3 comprises a first core piece 31, a second core piece 32, and a gap portion 33. The first core piece 31 and the second core piece 32 are assembled in a first direction D1 along the axis of the coil 2. The gap portion 33 is provided between the first core piece 31 and the second core piece 32. The molded resin portion 9 covers at least a part of the magnetic core 3. One of the features of the reactor 1 of Embodiment 1 is that the first end face 41e of the first middle core portion 41 provided on the first core piece 31 has a specific structure.

[0040] In the following description, we will use the first direction D1, the second direction D2, and the third direction D3 as defined below. The first direction D1 is the direction along the axis of the coil 2, from the first end face 20a to the second end face 20b of the coil 2. The second direction D2 is the direction perpendicular to the first direction D1, along the direction in which the first middle core portion 41, the first side core portion 51, and the second side core portion 52 are arranged in parallel. The third direction D3 is the direction perpendicular to both the first direction D1 and the second direction D2.

[0041] <<Coil>> As shown in Figures 1 to 3, 6 and 7, the coil 2 in this example has one winding section 20. In Figures 6 and 7, the coil 2 is shown with a dashed line for ease of explanation. The winding section 20 is constructed by winding a series of windings without joints in a spiral shape. Unlike this example, there may be multiple winding sections 20. In that case, the windings constituting each winding section 20 may be independent of each other or may be constructed in a series. The windings constituting each winding section 20 may be independent of each other, and each winding may be connected to each other by a member that electrically connects each winding to itself.

[0042] A coil 2 with one winding section 20 is easier to form than a coil 2 with multiple winding sections 20. A reactor 1 with one winding section 20 has fewer parts than a reactor 1 with multiple winding sections 20. Therefore, a reactor 1 with one winding section 20 has superior productivity. Having only one winding section 20 makes it easier to shorten the width of the reactor 1 compared to when multiple winding sections 20 are arranged in parallel in the second direction D2.

[0043] The shape of coil 2 in this example is rectangular, as shown in Figures 2 and 3. The outer circumference of coil 2, viewed along the first direction D1, is rectangular. That is, the end face shape of coil 2, viewed along the first direction D1, is rectangular. Because coil 2 is rectangular, it is easier to increase the contact area between coil 2 and the planar mounting surface compared to when coil 2 is circular with the same cross-sectional area. Therefore, reactor 1 can easily transfer heat from coil 2 to the mounting surface. The mounting surface is, for example, a cooling base. Furthermore, because the outer circumference of coil 2 is rectangular, it is easier to reduce the height of coil 2. Unlike this example, the shape of coil 2 may be a racetrack-shaped cylinder or a circular cylinder.

[0044] The windings in this example that make up coil 2 are insulated flat wires. The conductor wires of the insulated flat wires are made of copper flat wires. The insulating coating of the insulated flat wires is made of enamel. In this example, coil 2 is made by winding the insulated flat wires edgewise. Unlike this example, coil 2 may be made by winding the insulated flat wires flatwise. Unlike this example, the windings may be insulated round wires. The windings are known windings.

[0045] Although both ends of the winding are not shown in the figure, they are drawn out from the winding portion 20. Both ends of the winding have their insulating coatings peeled off to expose the conductor wires. Terminal members (not shown) are connected to the exposed conductor wires. External devices (not shown) are connected to the terminal members. The external device is, for example, a power source that supplies power to the coil 2.

[0046] ≪Magnetic Core≫ The magnetic core 3 of this example includes a middle core portion 4, a first side core portion 51, a second side core portion 52, a first end core portion 61, and a second end core portion 62. The magnetic core 3 forms a closed magnetic circuit by combining these core portions 4, 51, 52, 61, and 62. As shown in FIGS. 6 and 7, the planar shape of the magnetic core 3 of this example as viewed along the third direction D3 is a θ shape. In FIGS. 6 and 7, for convenience of explanation, the boundaries between the first middle core portion 41 and the first end core portion 61, between the first side core portion 51 and the second side core portion 52 and the first end core portion 61, and between the second middle core portion 42 and the second end core portion 62 are indicated by two-dot chain lines. The magnetic core 3 includes a first core piece 31, a second core piece 32, and a gap portion 33. The first core piece 31 and the second core piece 32 are combined along the first direction D1. The gap portion 33 is provided between the first core piece 31 and the second core piece 32.

[0047] The first core piece 31 of this example includes a low-μ portion 7a with a relatively low relative permeability and a high-μ portion 7b with a relatively high relative permeability. The magnetic core 3 controls the flow of magnetic flux by arranging regions with different relative permeabilities at predetermined locations. In FIGS. 1 - 3, 6, and 7, for convenience of explanation, the high-μ portion 7b is marked with cross-hatching. This is the same in FIGS. 12 and 13 referred to in Embodiment 5 described later. In the following description, in each of the side core portions 51, 52 and the end core portions 61, 62, the side farther from the winding portion 20 is called the outer side, and the side closer to the winding portion 20 is called the inner side.

[0048] [Middle Core Section] The middle core section 4 has a portion that is positioned inside the winding section 20. The shape of the middle core section 4 generally corresponds to the inner circumference shape of the winding section 20. In this example, the shape of the middle core section 4 is a rectangular columnar body. That is, the end face shape of the middle core section 4 when viewed from the first direction D1 is rectangular. A gap exists between the outer circumferential surface of the middle core section 4 and the inner circumferential surface of the winding section 20. This gap is filled with resin that constitutes the molded resin section 9, which will be described later.

[0049] The length of the middle core portion 4 along the first direction D1 is equal to or greater than the length of the winding portion 20 along the first direction D1. In this example, the length of the middle core portion 4 along the first direction D1 is slightly longer than the length of the winding portion 20 along the first direction D1, as shown in Figures 6 and 7. In other words, the middle core portion 4 comprises a portion located inside the winding portion 20 and a portion located outside the winding portion 20. Both ends of the middle core portion 4 are located outside the winding portion 20.

[0050] As shown in Figures 6 and 7, the middle core section 4 is composed of a first middle core section 41, a second middle core section 42, and a middle gap section 331, which will be described later. In this example, as shown in Figures 6 and 7, the width of the first middle core section 41 along the second direction D2 is the same as the width of the second middle core section 42 along the second direction D2.

[0051] As shown in Figures 4 and 5, the first middle core portion 41 has four outer circumferential surfaces facing the inner circumferential surface of the winding portion 20, and a first end surface 41e connected to the four outer circumferential surfaces. The four outer circumferential surfaces are the first surface 41a and the second surface 41b, which face each other in the third direction D3, and the third surface 41c and the fourth surface 41d, which face each other in the second direction D2. The first end surface 41e faces the second end surface 42e of the second middle core portion 42. The first end surface 41e connects to the first surface 41a, the second surface 41b, the third surface 41c, and the fourth surface 41d.

[0052] The first end face 41e of this example has a non-contact portion 41f and two protruding portions 41g. In Figure 5, for the sake of explanation, cross-hatching is applied to each protruding portion 41g. This is also the case for the protruding portion 41h in Figures 8, 10, and 11, which will be referenced in Embodiments 2 to 4 described later.

[0053] The non-contact portion 41f is positioned with a gap between it and the second end face 42e of the second middle core portion 42. That is, the non-contact portion 41f does not come into contact with the second end face 42e. A middle gap portion 331 is provided between the non-contact portion 41f and the second end face 42e.

[0054] Each protrusion 41g projects from the non-contact portion 41f toward the second end face 42e. Each protrusion 41g has a portion that contacts the second end face 42e. In this example, each protrusion 41g contacts the second end face 42e along its entire length in the third direction D3. Each protrusion 41g is provided extending from the first surface 41a to the second surface 41b. That is, each protrusion 41g is connected to the first surface 41a and the second surface 41b. The height H2 of each protrusion 41g along the third direction D3 is the same as the height H1 of the first end face 41e along the third direction D3. The two protrusions 41g are spaced apart from each other in the second direction D2.

[0055] When the molded resin portion 9 is molded, the resin constituting the molded resin portion 9 is filled from two directions: from the outside of the first end core portion 61 toward the inside of the winding portion 20, and from the outside of the second end core portion 62 toward the inside of the winding portion 20. Unlike this example, if the first end face 41e does not have two protrusions 41g, or if the height H2 is lower than the height H1, the distance between the non-contact portion 41f and the second end face 42e may become uneven in the third direction D3 due to the filling of the resin constituting the molded resin portion 9 from the two directions mentioned above. In contrast, in this example, by providing the two protrusions 41g described above, even if the resin constituting the molded resin portion 9 is filled from the two directions mentioned above, the two protrusions 41g sufficiently support the second end face 42e. Therefore, the distance between the non-contact portion 41f and the second end face 42e is more likely to be uniform in the third direction D3.

[0056] Of the two protrusions 41g in this example, the protrusion 41g located on the left side of Figure 5 is connected to the third surface 41c, and the remaining protrusion 41g located on the right side of Figure 5 is connected to the fourth surface 41d. That is, the outer width W3 along the second direction D2 of the two protrusions 41g is the same as the width W1 along the second direction D2 of the first end surface 41e.

[0057] The cross-sectional shape obtained by cutting each protrusion 41g with a cutting plane perpendicular to the third direction D3 is not particularly limited. The cross-sectional shape of each protrusion 41g may be, for example, rectangular, trapezoidal, or semicircular. In this example, the cross-sectional shape of each protrusion 41g is rectangular.

[0058] The protruding length L1, which is the maximum length of each protruding portion 41g along the first direction D1, is, for example, 2.0% to 20% of the length of the middle core portion 4 along the first direction D1. If the protruding length L1 is 2.0% or more of the above length of the middle core portion 4, the middle gap portion 331 provided between the non-contact portion 41f and the second end face 42e is likely to have the desired volume. If the protruding length L1 is 20% or less of the above length of the middle core portion 4, the length of the middle core portion 4 along the first direction D1 does not become too long, making it easier to miniaturize the reactor 1. The protruding length L1 may also be 3.0% to 15% or 4.0% to 12% of the above length of the middle core portion 4.

[0059] The width W2, which is the maximum length of each protrusion 41g along the second direction D2, is, for example, 3.0% to 30% of the width W1, which is the length of the first end face 41e along the second direction D2. If the width W2 is 3.0% or more of the width W1, the distance between the non-contact portion 41f and the second end face 42e tends to be uniform in the third direction D3. If the width W2 is 30% or less of the width W1, the middle gap portion 331 provided between the non-contact portion 41f and the second end face 42e tends to have the desired volume. The width W2 may also be 4.0% to 25% or 5.0% to 20% of the width W1.

[0060] [First side core section and second side core section] The first side core section 51 and the second side core section 52 are arranged on the outside of the winding section 20, alongside the middle core section 4. The first side core section 51 and the second side core section 52 are arranged so as to sandwich the winding section 20 from the outside. The first side core section 51, the second side core section 52, and the middle core section 4 are arranged in parallel in the second direction D2.

[0061] The shape of each side core portion 51, 52 is not particularly limited as long as it extends along the first direction D1 on the outside of the winding portion 20. In this example, each side core portion 51, 52 is a rectangular columnar body extending along the first direction D1. In this example, where the shape of the winding portion 20 is a rectangular cylinder, each side core portion 51, 52 is arranged to face two of the four faces that constitute the outer circumferential surface of the winding portion 20, which are opposite each other. The remaining two faces of the winding portion 20 do not face the magnetic core 3.

[0062] In this example, the shape and dimensions of both side core portions 51 and 52 are identical. The length of each side core portion 51 and 52 along the first direction D1 is shorter than the length of the middle core portion 4 along the first direction D1. In this example, the sum of the cross-sectional areas of the first side core portion 51 and the second side core portion 52 is the same as the cross-sectional area of ​​the middle core portion 4. Here, the cross-sectional area is the cross-sectional area of ​​the cutting surface perpendicular to the first direction D1 in each core portion 4, 51, and 52. In this example, the length of each side core portion 51 and 52 along the second direction D2 is shorter than the length of the middle core portion 4 along the second direction D2. In this example, the sum of the length of the first side core portion 51 along the second direction D2 and the length of the second side core portion 52 along the second direction D2 is shorter than the length of the middle core portion 4 along the second direction D2. In this example, the length of each side core portion 51, 52 along the third direction D3 is the same as the length of the first middle portion 411 along the third direction D3. All surfaces of the core portions 41, 42, 51, 52, 61, 62 facing the third direction D3 are flush. All surfaces of the core portions 41, 42, 51, 52, 61, 62 facing away from the third direction D3 are flush.

[0063] Unlike this example, the total length of each side core section 51, 52 along the second direction D2 may be the same as the length of the middle core section 4 along the second direction D2, or it may be shorter than the length of the middle core section 4 along the second direction D2. The length of each side core section 51, 52 along the third direction D3 may be shorter than the length of the middle core section 4 along the third direction D3, or it may be longer than the length of the middle core section 4 along the third direction D3. The length of each side core section 51, 52 along the third direction D3 may be shorter than the length of the winding section 20 along the third direction D3. The length of each side core section 51, 52 along the third direction D3 may be equal to or greater than the length of the winding section 20 along the third direction D3. The shapes and dimensions of both side core sections 51, 52 may be different from each other.

[0064] [First End Core Section and Second End Core Section] The first end core section 61 is positioned on the outside of the first end face 20a of the winding section 20, facing the first end face 20a. The first end core section 61 connects the first middle core section 41 and both side core sections 51 and 52. The second end core section 62 is positioned on the outside of the second end face 20b of the winding section 20, facing the second end face 20b. The second end core section 62 is positioned to connect to the second middle core section 42.

[0065] The shape of each end core portion 61, 62 is not particularly limited. In this example, each end core portion 61, 62 is a rectangular columnar body that is elongated in the second direction D2. In this example, the shape and dimensions of both end core portions 61, 62 are the same. The length of each end core portion 61, 62 along the first direction D1 is the same as the length of each side core portion 51, 52 along the second direction D2. The length of each end core portion 61, 62 along the third direction D3 is the same as the length of each side core portion 51, 52 along the third direction D3. The shape and dimensions of both end core portions 61, 62 may be different from each other.

[0066] [First Core Piece and Second Core Piece] As shown in Figures 1 to 3, 6, and 7, the magnetic core 3 in this example is constructed by combining a first core piece 31 and a second core piece 32 such that a gap 33 is provided between the first core piece 31 and the second core piece 32. The shapes of the first core piece 31 and the second core piece 32 may be symmetrical or asymmetrical. Symmetrical means that the shape and size are the same. Asymmetrical means that the shapes are different. In this example, the shapes of the first core piece 31 and the second core piece 32 are asymmetrical. In this example, the planar shape of the first core piece 31 is E-shaped. The planar shape of the second core piece 32 is T-shaped. In the case of a combination of an E-shaped first core piece 31 and a T-shaped second core piece 32, unlike this example, if there are no two protruding portions 41g, when the resin constituting the molded resin portion 9 is filled from the two directions, the distance between the non-contact portion 41f and the second end face 42e tends to become uneven in the third direction D3. However, in this example, since there are two protruding portions 41g, even if the combination of an E-shaped first core piece 31 and a T-shaped second core piece 32 is used and the resin constituting the molded resin portion 9 is filled from the two directions, the distance between the non-contact portion 41f and the second end face 42e tends to become uniform in the third direction D3. The first core piece 31 in this example comprises a first end core portion 61, a first middle core portion 41, a first side core portion 51, and a second side core portion 52. The second core piece 32 in this example comprises a second end core portion 62 and a second middle core portion 42.

[0067] As shown in Figures 2, 3, 6, and 7, the first core piece 31 in this example is composed of a low-μ portion 7a and a high-μ portion 7b with different relative permeability. The relative permeability of the high-μ portion 7b is higher than that of the low-μ portion 7a. Typically, the first core piece 31 is manufactured by placing the high-μ portion 7b in a mold and molding the low-μ portion 7a around it. In Figures 2 and 3, for the sake of explanation, the low-μ portion 7a and the high-μ portion 7b are shown separately, but in reality they are formed as a single unit. The first core piece 31 may also be composed of individually molded low-μ portion 7a and high-μ portion 7b combined. Unlike the first core piece 31, the second core piece 32 in this example is composed of a single portion.

[0068] <Low μ portion> The planar shape of the low μ portion 7a in this example is E-shaped, as shown in Figures 6 and 7. The low μ portion 7a in this example has a first end portion 611 which is part of the first end core portion 61, a first middle portion 411 which is part of the first middle core portion 41, and two side core portions 51 and 52. The first end portion 611, the first middle portion 411, and the two side core portions 51 and 52 are integrally formed.

[0069] The first end portion 611 is a portion located on the inside of the first end core portion 61. The first end portion 611 consists of a first portion facing the winding portion 20 and a second portion connected to both side core portions 51 and 52. The first portion and the second portion of the first end portion 611 are integrally formed.

[0070] As shown in Figure 6, the first middle portion 411 is composed of a first portion that covers both sides of the protruding portion 73 facing the second direction D2, and a second portion that protrudes from the first portion toward the second middle core portion 42. The tip surface of the protruding portion 73 is covered by the second portion of the first middle portion 411. The first portion and the second portion of the first middle portion 411 are integrally formed.

[0071] Each first corner 74 is formed by the first and second portions of the first end portion 611 and the first portion of the first middle portion 411. Each second corner 75 is formed by the first and second portions of the first end portion 611 and the side core portions 51 and 52.

[0072] As shown in Figure 3, a recess 71 corresponding to the shape of the high-μ portion 7b is formed in the low-μ portion 7a. In this example, the recess 71 is formed corresponding to the protruding portion 73. A part of the low-μ portion 7a is positioned in the inner region extending from the base end portion 72 to the protruding portion 73, which will be described later. This low-μ portion 7a integrally constitutes the first end core portion 61, the first middle core portion 41, and both side core portions 51 and 52.

[0073] <High μ portion> The high μ portion 7b has a base portion 72 extending in the second direction D2 and a protruding portion 73 extending in the first direction D1. The base portion 72 and the protruding portion 73 are integrally formed. The planar shape of the high μ portion 7b in this example is T-shaped, as shown in Figures 6 and 7. The base portion 72 and the protruding portion 73 are rectangular columnar bodies. The base portion 72 and a part of the protruding portion 73 form the second end portion 612, which is part of the first end core portion 61. The first end core portion 61 is composed of a first end portion 611 and a second end portion 612. The shape of the first end portion 611 is a thin rectangular columnar body. The shape of the second end portion 612 is a T-shaped columnar body. The tip portion of the protruding portion 73 is the second middle portion 412, which is part of the first middle core portion 41. The first middle core section 41 is composed of a first middle section 411 and a second middle section 412.

[0074] <Base End Position> The base end position 72 is located off-center to the outside of the first end core portion 61. That is, the base end position 72 is provided at a distance from the surface of the first end core portion 61 that faces the first end face 20a of the winding portion 20.

[0075] The base end portion 72 is provided in the first end core portion 61 so as to extend along the second direction D2, straddling the axis 410 of the first middle core portion 41. In Figures 6 and 7, the axis 410 is shown as a dashed line. The axis 410 is a straight line extending from the center line of the first middle core portion 41. As described above, the cross-sectional shape of the middle core portion 4 in this example is rectangular. Therefore, the axis 410 in this example is a straight line extending along the first direction D1, passing through the intersection of the diagonals of the rectangle. When viewed from a third direction D3, the axis 410 in this example is a straight line extending along the first direction D1 of the first middle core portion 41 so as to bisect the length of the first middle core portion 41 along the second direction D2.

[0076] The base end portion 72 may extend beyond each first corner portion 74 in the second direction D2 in the first end core portion 61. In this example, the base end portion 72 is provided at both ends along the second direction D2 in the first end core portion 61. In other words, unlike this example, both ends of the base end portion 72 along the second direction D2 may be located in a region corresponding to the area between the first corner portion 74 and the second corner portion 75. More specifically, both ends of the base end portion 72 along the second direction D2 may be located in a region that is flush with the outer surface of the winding portion 20.

[0077] 《Protruding portion》 The protruding portion 73 protrudes from the base end portion 72 toward the second middle core portion 42. In this example, the protruding portion 73 is provided spanning from the first end core portion 61 to the first middle core portion 41. The protruding portion 73 has the function of attracting the magnetic flux flowing from the first middle core portion 41 toward the first end core portion 61, or the function of guiding the magnetic flux flowing from the first end core portion 61 toward the first middle core portion 41 into the winding portion 20. Having either of these functions reduces the leakage magnetic flux from the first corner portion 74. The shape of the protruding portion 73 is not particularly limited as long as it has either of these functions. In this example, the protruding portion 73 is a rectangular parallelepiped extending along the first direction D1.

[0078] The tip surface of the protruding portion 73 does not reach the first end surface 20a of the winding portion 20 and may be located outside the winding portion 20, flush with the first end surface 20a of the winding portion 20, or located inside the winding portion 20. In this example, the tip surface is located inside the winding portion 20, as shown in Figure 6. By having the tip surface located inside the winding portion 20, leakage flux is easily suppressed even if a misalignment occurs due to dimensional tolerances during the assembly of the coil 2 and the magnetic core 3, or if compression of the winding portion 20 occurs due to the molding pressure of the molded resin portion 9. The length along the first direction D1 between the first end surface 20a of the winding portion 20 and the tip surface inside the winding portion 20 is, for example, 1 / 10 or less, 1 / 20 or less, or 1 / 30 or less of the total length of the winding portion 20.

[0079] [Gap Section] The gap section 33 has a middle gap section 331, a first side gap section 332, and a second side gap section 333. By providing the gap section 33, the inductance of the reactor 1 can be easily adjusted. The middle gap section 331 is provided between the non-contact section 41f on the first end face 41e of the first middle core section 41 and the second end face 42e of the second middle core section 42. The middle gap section 331 is located inside the winding section 20. The first side gap section 332 is provided between the first side core section 51 and the second end core section 62. The second side gap section 333 is provided between the second side core section 52 and the second end core section 62. Unlike this example, if the molded resin portion 9 is formed without the two side gap portions 332 and 333, and the two side core portions 51 and 52 are in contact with the second end core portion 62, the filling of the resin constituting the molded resin portion 9 from the two directions may cause the first core piece 31 to tilt, potentially creating a gap between at least one of the two protrusions 41g and the second end face 42e. In that case, the distance between the non-contact portion 41f and the second end face 42e tends to be uneven in the third direction D3. However, by having the first side gap portion 332 and the second side gap portion 333 as in this example, the molded resin portion 9 can be formed with sufficient contact between the two protrusions 41g of the first middle core portion 41 and the second end face 42e of the second middle core portion 42. Therefore, the distance between the non-contact portion 41f and the second end face 42e tends to be uniform in the third direction D3.

[0080] The gap portion 33 is made of a material having a lower relative magnetic permeability than the first core piece 31 and the second core piece 32. The material used for the gap portion 33 can preferably be, for example, a non-magnetic ceramic or resin. The gap portion 33 may also be an air gap. The gap portion 33 may also be part of the molded resin portion 9, which will be described later. In this example, the gap portion 33 is part of the molded resin portion 9.

[0081] <Relative Permeability> As mentioned above, the relative permeability of the high-μ region 7b is greater than that of the low-μ region 7a. While satisfying the above relationship of relative permeability, the relative permeability of the low-μ region 7a is, for example, 5 to 50. Also, the relative permeability of the high-μ region 7b is, for example, 50 to 500. By satisfying the above upper and lower limits for the relative permeability of the low-μ region 7a, magnetic saturation associated with the presence of the high-μ region 7b is less likely to occur, making it easier to maintain high inductance even in high-current operating environments. By satisfying the above upper and lower limits for the relative permeability of the high-μ region 7b, magnetic flux can easily pass through the high-μ region 7b, making it easier to reduce leakage flux. The relative permeability of the low-μ region 7a may be 10 to 45, or 15 to 40. The relative permeability of the high-μ region 7b may be 55 to 450, or 60 to 400.

[0082] The relative permeability of each section is determined as follows: Ring-shaped measurement samples are cut from the low-μ section 7a and the high-μ section 7b, respectively. Each measurement sample is wound with 300 turns on the primary side and 20 turns on the secondary side. The B-H initial magnetization curve is measured in the range H = 0 (Oe) to 100 (Oe), and the maximum value of the slope of this B-H initial magnetization curve is determined. This maximum value is taken as the relative permeability. The magnetization curve here is what is known as the DC magnetization curve.

[0083] <Material> The low-μ portion 7a and high-μ portion 7b of the first core piece 31 are made of molded bodies with different relative permeability. The molded bodies are either powder compacted bodies or molded bodies of composite materials. A powder compacted body is a molded body made by compression molding of soft magnetic powder. A molded body of composite materials is a molded body in which soft magnetic powder is dispersed in resin. For example, even if the low-μ portion 7a and the high-μ portion 7b are made of powder compacted bodies, if the material and content ratio of the soft magnetic powder constituting the powder compacted bodies are different, their relative permeability will be different. Also, even if the low-μ portion 7a and the high-μ portion 7b are made of composite material molded bodies, if the material of at least one of the soft magnetic powder and resin constituting the composite material is different, or even if the material of the soft magnetic powder and resin is the same, if the content ratio of the soft magnetic powder and resin is different, their relative permeability will be different. Therefore, the low-μ portion 7a and the high-μ portion 7b may be composed of a compacted molded body, or the low-μ portion 7a and the high-μ portion 7b may be composed of a molded body of a composite material, or the low-μ portion 7a may be composed of a molded body of a composite material and the high-μ portion 7b may be composed of a compacted molded body. In this example, the low-μ portion 7a is composed of a molded body of a composite material and the high-μ portion 7b is composed of a compacted molded body.

[0084] In molded composite materials, the content ratio of soft magnetic powder in the resin can be easily adjusted. Therefore, the magnetic properties of molded composite materials are easy to adjust. Furthermore, molded composite materials are easier to form into complex shapes compared to compacted powder molded materials. The content ratio of soft magnetic powder in the molded composite material is, for example, 20% to 80% by volume. The content ratio of resin in the molded composite material is, for example, 20% to 80% by volume. These content ratios are relative to the total volume of the molded composite material, which is set at 100%.

[0085] Compared to molded bodies made from composite materials, powder compacted bodies can have a higher proportion of soft magnetic powder in the magnetic core 3. Therefore, powder compacted bodies can easily have enhanced magnetic properties. Magnetic properties include relative permeability and saturation magnetic flux density. Furthermore, powder compacted bodies have superior heat dissipation because they contain less resin and more soft magnetic powder compared to molded bodies made from composite materials. The soft magnetic powder content in the powder compacted body is, for example, 85% to 99% by volume. This content is a ratio relative to the total volume of the powder compacted body, which is set at 100%.

[0086] The particles constituting the soft magnetic powder are, for example, particles of soft magnetic metal, coated particles, or particles of soft magnetic nonmetal. The coated particles consist of soft magnetic metal particles and an insulating coating provided on the outer circumference of the soft magnetic metal particles. The soft magnetic metal is, for example, pure iron or an iron-based alloy. The iron-based alloy is, for example, an Fe-Si alloy or an Fe-Ni alloy. The insulating coating is, for example, a phosphate. The soft magnetic nonmetal is, for example, ferrite.

[0087] The resin in a composite molded article is, for example, a thermosetting resin or a thermoplastic resin. Thermosetting resins include, for example, epoxy resins, phenolic resins, silicone resins, or urethane resins. Thermoplastic resins include, for example, polyphenylene sulfide (PPS) resins, polyamide (PA) resins, liquid crystal polymers (LCP), polyimide resins, or fluororesins. PA resins include, for example, nylon 6, nylon 66, or nylon 9T.

[0088] The molded composite material may contain fillers. These fillers are non-magnetic powders, such as alumina or silica. The fillers contribute to improved heat dissipation and electrical insulation.

[0089] The content ratio of soft magnetic powder in a composite material molded body and in a compacted powder molded body is considered equivalent to the area ratio of soft magnetic powder in the cross-section of the molded body. The content ratio of soft magnetic powder in the molded body is determined as follows: Observe the cross-section of the molded body with an SEM (scanning electron microscope) and acquire an observation image. The cross-section of the molded body can be any cross-section. The SEM magnification should be between 200x and 500x. Acquire at least 10 observation images. The total cross-sectional area should be 0.1 cm². ２ The above procedure is followed. One observation image may be obtained for each cross-section, or multiple observation images may be obtained for each cross-section. Each obtained observation image is processed to extract the contours of the particles. For example, binarization can be used as an image processing method. The area ratio of soft magnetic particles is calculated for each observation image, and the average value of these area ratios is determined. This average value is considered to be the content ratio of soft magnetic powder.

[0090] The second core piece 32 is composed of either a compacted powder body or a molded composite material body. The compacted powder body or molded composite material body that constitutes the second core piece 32 may be the same as or different from the compacted powder body or molded composite material body that constitutes the first core piece 31. In this example, the second core piece 32 is composed of the same compacted powder body that constitutes the high μ portion 7b of the first core piece 31.

[0091] ≪Molded Resin Part≫ As shown in Figure 1, the molded resin part 9 covers at least a portion of the magnetic core 3. The molded resin part 9 has the function of protecting the magnetic core 3 from the external environment. The molded resin part 9 may also cover the coil 2. In other words, the molded resin part 9 is provided so as to cover at least a portion of the combination of the coil 2 and the magnetic core 3. The entire combination may be covered by the molded resin part 9, or at least one of the first and second surfaces of the outer circumferential surface of the winding part 20 that face each other in the third direction D3 may be exposed from the molded resin part 9 without being covered. In this example, both the first and second surfaces of the winding part 20 are exposed from the molded resin part 9. If the molded resin part 9 is interposed between the coil 2 and the magnetic core 3, it is easier to insulate the coil 2 and the magnetic core 3.

[0092] In this example, the molded resin portion 9 covers the outer circumference of the assembly of the coil 2 and the magnetic core 3. Therefore, the assembly in this example is protected from the external environment by the molded resin portion 9. Furthermore, the assembly in this example is constructed by integrating the coil 2 and the magnetic core 3 with the molded resin portion 9. At least a portion of the outer surface of the magnetic core 3, or at least a portion of the outer surface of the coil 2, may be exposed from the molded resin portion 9.

[0093] In this example, the molded resin portion 9 is interposed between the inner surface of the winding portion 20 and the middle core portion 4. Furthermore, the molded resin portion 9 in this example is filled between the non-contact portion 41f of the first middle core portion 41 and the second end face 42e of the second middle core portion 42, forming the middle gap portion 331. In addition, the molded resin portion 9 in this example is filled between the first side core portion 51 and the second end core portion 62, and between the second side core portion 52 and the second end core portion 62, forming the first side gap portion 332 and the second side gap portion 333.

[0094] The resin constituting the molded resin portion 9 may include, for example, the resins listed in the description of the composite material resin above. The constituent material of the molded resin portion 9 may also contain the filler described above.

[0095] [Embodiment 2] <Reactor> The reactor of Embodiment 2 shown in Figure 8 differs from the reactor 1 of Embodiment 1 in that the positions of the two protrusions 41g of the first middle core portion 41 are different. The following explanation will focus on the differences from Embodiment 1. Explanations of the same or similar configurations and effects as in Embodiment 1 will be omitted. These points are also the same in Embodiments 3 and 5, which will be described later.

[0096] [Middle Core Section] Of the two protrusions 41g, the one located on the left side of Figure 8 is not directly connected to the third surface 41c, and the other protrusion 41g located on the right side of Figure 8 is not directly connected to the fourth surface 41d. The outer width W3 along the second direction D2 of the two protrusions 41g is smaller than the width W1 along the second direction D2 of the first end surface 41e. Non-contact sections 41f are provided between the two protrusions 41g, between the protrusion 41g located on the left side of Figure 8 and the third surface 41c, and between the protrusion 41g located on the right side of Figure 8 and the fourth surface 41d.

[0097] In this example, the distance C1 along the second direction D2 between the protruding portion 41g located on the left side of Figure 8 and the third surface 41c, and the distance C2 along the second direction D2 between the protruding portion 41g located on the right side of Figure 8 and the fourth surface 41d, are the same. Each distance C1 and C2 is, for example, 5.0% to 30% of the width W1. If each distance C1 and C2 is 5.0% or more of the width W1, the distance between the two protruding portions 41g tends to be small, making it easier for the two protruding portions 41g to support the second end surface 42e. If each distance C1 and C2 is 30% or less of the width W1, the distance between the two protruding portions 41g does not become too small. Therefore, even if the resin constituting the molded resin portion 9 is filled from the two directions mentioned above, the distance between the non-contact portion 41f and the second end surface 42e tends to be uniform in the third direction D3. Each distance C1 and C2 may be 7.5% to 25% or 10% to 20% of the width W1.

[0098] [Embodiment 3] <Reactor> The reactor of Embodiment 3 shown in Figures 9 and 10 differs from the reactor 1 of Embodiment 1 in that the first middle core portion 41 has four protruding pieces 41h instead of two protruding portions 41g.

[0099] [Middle Core Section] The four projections 41h consist of two first projections 41i arranged near the first surface 41a at intervals from each other in the second direction D2, and two second projections 41k arranged near the second surface 41b at intervals from each other in the second direction D2. The four projections 41h are provided at the four corners of the rectangular first end surface 41e. Of the two first projections 41i, one located in the upper left of Figure 10 connects the first surface 41a and the third surface 41c, and the remaining first projection 41i located in the upper right of Figure 10 connects the first surface 41a and the fourth surface 41d. Of the two second projections 41k, the one located in the lower left of Figure 10 connects to the second surface 41b and the third surface 41c, while the remaining second projection 41k located in the lower right of Figure 10 connects to the second surface 41b and the fourth surface 41d. The outer height H3 along the third direction D3 between the first projection 41i located in the upper left of Figure 10 and the second projection 41k located in the lower left, and the outer height H3 along the third direction D3 between the first projection 41i located in the upper right of Figure 10 and the second projection 41k located in the lower right, are the same. The outer height H3 is the same as the height H1, which is the length of the first end surface 41e along the third direction D3. The non-contact portion 41f is provided in a plus sign shape between the four projections 41h.

[0100] The protruding length L1, which is the maximum length of each protruding piece 41h along the first direction D1, is the same as the protruding length L1 of each ridged portion 41g along the first direction D1 as described in Embodiment 1. The width W2, which is the length of each protruding piece 41h along the second direction D2, is the same as the width W2 of each ridged portion 41g as described in Embodiment 1. The height H2, which is the length of each protruding piece 41h along the third direction D3, is, for example, 5.0% or more and 30% or less of the height H1. If the height H2 is 5.0% or more of the height H1, even if the resin constituting the molded resin portion 9 is filled from the two directions mentioned above, the distance between the non-contact portion 41f and the second end face 42e tends to become uniform in the third direction D3. If the height H2 is 30% or less of the height H1, the middle gap portion 331 provided between the non-contact portion 41f and the second end face 42e tends to have the desired volume. Height H2 may be 6.5% to 25% or 8.0% to 20% of height H1.

[0101] [Embodiment 4] <Reactor> The reactor of Embodiment 4 shown in Figure 11 differs from the reactor of Embodiment 3 in that the positions of the four protruding pieces 41h of the first middle core portion 41 are different. The following description will focus on the differences from Embodiment 3. Descriptions of the same or similar configurations and effects as in Embodiment 3 will be omitted.

[0102] [Middle Core Section] The four projections 41h are not directly connected to any of the first surface 41a, second surface 41b, third surface 41c, and fourth surface 41d. The outer widths W3 along the second direction D2 for the two first projections 41i and the two second projections 41k are the same and smaller than the width W1 along the second direction D2 of the first end surface 41e. The outer heights H3 along the third direction D3 for the first projection 41i located in the upper left of Figure 11 and the second projection 41k located in the lower left, and the outer heights H3 along the third direction D3 for the first projection 41i located in the upper right of Figure 11 and the second projection 41k located in the lower right, are the same. The outer heights H3 are smaller than the height H1, which is the length along the third direction D3 of the first end surface 41e. The non-contact portion 41f has an outer peripheral portion provided in the shape of a rectangular frame so as to surround the four protruding portions 41h together, and a central portion provided in the shape of a plus sign between the four protruding portions 41h and the outer peripheral portion.

[0103] The distance C1 along the second direction D2 between each of the first projection 41i in the upper left of Figure 11 and the second projection 41k in the lower left of Figure 11 and the third surface 41c, the distance C2 along the second direction D2 between each of the first projection 41i in the upper right of Figure 11 and the second projection 41k in the lower right of Figure 11 and the fourth surface 41d, the distance C3 along the third direction D3 between each of the two first projections 41i and the first surface 41a, and the distance C4 along the third direction D3 between each of the two second projections 41k and the second surface 41b are uniform. Each distance C1 and C2 is the same as the distances C1 and C2 described in Embodiment 2. Each distance C3 and C4 is 5.0% or more and 30% or less of the height H1, which is the length of the first end surface 41e along the third direction D3. If each distance C3 and C4 is 5.0% or more of the height H1, the resin of the molded resin part 9 is easily filled into the middle gap 331. If each distance C3 and C4 is 30% or less of the height H1, even if the resin constituting the molded resin part 9 is filled from the two directions mentioned above, the distance between the non-contact part 41f and the second end face 42e is easily uniform in the third direction D3. Each distance C3 and C4 may be 6.5% to 25% or 8.0% to 20% of the height H1.

[0104] [Embodiment 5] <Reactor> The reactor of Embodiment 5 shown in Figures 12 and 13 differs from the reactor 1 of Embodiment 1 in that the high μ portion 7b has a low step portion 76 in which the edges of the first and second surfaces facing the third direction D3 of the high μ portion 7b are locally lowered.

[0105] The lower step portion 76 is provided on the edges of the first and second surfaces of the high-μ portion 7b that connect to the low-μ portion 7a. In this example, the lower step portion 76 consists of the inner edges 721 of the first and second surfaces of the base end portion 72 of the high-μ portion 7b, and the tip edge 731 and both side edges 732 of the first and second surfaces of the protruding portion 73. The lower step portion 76 is covered by the low-μ portion 7a. Therefore, the high-μ portion 7b and the low-μ portion 7a are easily joined together firmly.

[0106] The step difference, which is the length along the third direction D3 between the area excluding the lower step portion 76 on each of the first and second surfaces and the lower step portion 76, is, for example, 1 mm or more and 10 mm or less. If the step difference is 1 mm or more, the high μ portion 7b and the low μ portion 7a are more easily joined firmly. If the step difference is 10 mm or less, the volume of the high μ portion 7b is less likely to decrease, making it easier to attract magnetic flux. The step difference may also be 1 mm or more and 7 mm or less, 1 mm or more and 4 mm or less, or 1 mm or more and 3 mm or less.

[0107] [Embodiment 6] <Converter / Power Conversion Device> The reactor 1 of any of Embodiments 1 to 5 can be used for applications that satisfy the following energizing conditions. The maximum DC current is, for example, about 100A to 1000A. The average voltage is, for example, about 100V to 1000V. The operating frequency is, for example, about 5kHz to 100kHz. The reactor 1 of any of Embodiments 1 to 5 can typically be used as a component of a converter mounted on a vehicle 1200 such as an electric vehicle, a hybrid vehicle, or a fuel cell vehicle, or as a component of a power conversion device equipped with this converter.

[0108] As shown in Figure 14, the vehicle 1200 includes a main battery 1210, a power converter 1100 connected to the main battery 1210, and a motor 1220 that is driven by power supplied from the main battery 1210 and used for driving. The motor 1220 is typically a three-phase AC motor. The motor 1220 drives the wheels 1250 when driving and functions as a generator during regeneration. In the case of a hybrid vehicle, the vehicle 1200 is equipped with an engine 1300 in addition to the motor 1220. In Figure 14, an inlet is shown as the charging point of the vehicle 1200, but it can also be equipped with a plug.

[0109] The power conversion device 1100 includes a converter 1110 and an inverter 1120. The converter 1110 is connected to the main battery 1210. The inverter 1120 is connected to the converter 1110. The inverter 1120 performs mutual conversion between DC and AC. In this example, the converter 1110, when the vehicle 1200 is running, boosts the input voltage of the main battery 1210, which is approximately 200V to 300V, to approximately 400V to 700V and supplies power to the inverter 1120. During regeneration, the converter 1110 steps down the input voltage output from the motor 1220 via the inverter 1120 to a DC voltage suitable for the main battery 1210 and charges the main battery 1210. The input voltage is a DC voltage. When the vehicle 1200 is running, the inverter 1120 converts the DC boosted by the converter 1110 into a predetermined AC and supplies power to the motor 1220. During regeneration, the inverter 1120 converts the AC output from the motor 1220 into DC and outputs it to the converter 1110.

[0110] As shown in Figure 15, the converter 1110 comprises a plurality of switching elements 1111, a drive circuit 1112 that controls the operation of the switching elements 1111, and a reactor 1115. The converter 1110 converts the input voltage by repeatedly switching ON / OFF. In this case, the input voltage conversion is step-up or step-down. Power devices such as field-effect transistors and insulated-gate bipolar transistors are used as switching elements 1111. The reactor 1115 utilizes the coil property of trying to hinder changes in the current that is trying to flow through the circuit, and has the function of smoothing the change when the current tries to increase or decrease due to the switching operation. The reactor 1115 is provided as reactor 1 of any of Embodiments 1 to 5. Power conversion devices 1100 and converters 1110 equipped with reactor 1 have excellent performance.

[0111] Vehicle 1200 includes a converter 1110, a power supply converter 1150, and an auxiliary power converter 1160. The power supply converter 1150 is connected to the main battery 1210. The auxiliary power converter 1160 is connected to the main battery 1210 and a sub-battery 1230, which is the power source for the auxiliary equipment 1240. The auxiliary power converter 1160 converts the high voltage of the main battery 1210 to low voltage. The converter 1110 typically performs DC-DC conversion, while the power supply converter 1150 and the auxiliary power converter 1160 perform AC-DC conversion. Some power supply converters 1150 also perform DC-DC conversion. The reactors of the power supply converter 1150 and the auxiliary power converter 1160 have substantially the same configuration as reactor 1 of any of Embodiments 1 to 5, and reactors with appropriately modified size and shape can be used. Furthermore, for a converter that converts input power, such as a converter that only boosts voltage or a converter that only bucks voltage, any of the reactors 1 from Embodiment 1 to Embodiment 5 can be used.

[0112] [Test Example] In the test example, the difference in uniformity of the distance between the non-contact portion and the second end face of the second middle core portion due to differences in the configuration of the first end face of the first middle core portion was evaluated.

[0113] <Sample No. 1> In Sample No. 1, a combination of the coil 2 and magnetic core 3 of Embodiment 1, as described with reference to Figures 1 to 7, was prepared. The combination was placed in a mold with the two protrusions 41g of the first end face 41e of the first middle core portion 41 in contact with the second end face 42e of the second middle core portion 42. The resin constituting the molded resin portion 9 was filled and solidified from two directions: from the outside of the first end core portion 61 toward the inside of the winding portion 20, and from the outside of the second end core portion 62 toward the inside of the winding portion 20.

[0114] <Sample No. 101> Sample No. 101 differs from Sample No. 1 in that the first end face 41e of the first middle core portion 41 has two protruding parts (not shown). The two protruding parts are located at both ends of the second direction D2 on the first end face 41e and in the center of the third direction D3. The length of each protruding part along the first direction D1 is the same as the length of each rib portion 41g of Sample No. 1 along the first direction D1. The length of each protruding part along the second direction D2 is the same as the length of each rib portion 41g of Sample No. 1 along the second direction D2. The length of each protruding part along the third direction D3 is 50% of the length of the first end face 41e along the third direction D3.

[0115] <Evaluation of Uniformity> After the resin constituting the molded resin part 9 had solidified, each sample was cut by a cross-section perpendicular to the second direction D2 passing through the axis 410. At three points, from the first to the third point, between the non-contact part 41f and the second end face 42e in the cross-section of each sample, the distance along the first direction D1 between the non-contact part 41f and the second end face 42e was measured. The first point is a point passing through the axis 410. The second point is the midpoint between the first point and the first surface 41a. The third point is the midpoint between the first point and the second surface 41b. In other words, the above distance was calculated at three points in the third direction D3: the upper, middle, and lower parts. The difference between the maximum and minimum values ​​of the above distance at the three points was calculated.

[0116] The above difference in sample No. 1 was 0.000 mm. The above difference in sample No. 101 was 0.186 mm. In sample No. 1, it was found that the area between the non-contact portion 41f and the second end face 42e was uniform.

[0117] The present invention is not limited to these examples, but is intended to include all modifications within the meaning and scope of the claims as shown, and equivalents thereto. It should be understood that at least one configuration or feature described in each embodiment can be combined with other embodiments or modified in various ways.

[0118] For example, the combination of the first core piece and the second core piece may be of the E-T type as described in Embodiment 1, etc., or of the E-E type, F-F type, F-L type, or U-T type. Furthermore, the high μ portion may have side protruding portions that protrude from both ends in the direction along the second direction D2 toward the first side core portion and the second side core portion.

[0119] 1 Reactor 2 Coil, 20 Winding section, 20a First end face, 20b Second end face 3 Magnetic core, 31 First core piece, 32 Second core piece, 33 Gap section 331 Middle gap section 332 First side gap section, 333 Second side gap section 4 Middle core section 41 First middle core section, 410 Axis 411 First middle section, 412 Second middle section 41a First surface, 41b Second surface, 41c Third surface, 41d Fourth surface 41e First end face, 41f Non-contact section, 41g Protrusion section 41h Protrusion section, 41i First protrusion section, 41k Second protrusion section 42 Second middle core section, 42e Second end face 51 First side core section, 52 Second side core section 61 First end core section, 611 1st end section, 612 2nd end section, 62 2nd end core section, 7a Low μ section, 71 Recessed section, 7b High μ section, 72 Base end section, 721 Inner edge section, 73 Protruding section, 731 Front edge section, 732 Side edge section, 74 1st corner section, 75 2nd corner section, 76 Low step section, 9 Molded resin section, 1100 Power converter, 1110 Converter, 1111 Switching element, 1112 Drive circuit, 1115 Reactor, 1120 Inverter, 1150 Converter for power supply device, 1160 Converter for auxiliary power supply, 1200 Vehicle, 1210 Main battery, 1220 Motor, 1230 Sub-battery, 1240 Auxiliary equipment, 1250 Wheels, 1300 Engine, C1, C2, C3, C4 Distance, H1, H2 Height H3 Outer height, L1 Projection length, W1, W2 Width, W3 Outer width

Claims

1. A magnetic core comprising a coil, a first core piece and a second core piece combined in a first direction along the axis of the coil, a gap portion provided between the first core piece and the second core piece, and a molded resin portion covering at least a part of the magnetic core, wherein the first core piece has a plurality of parallel core pieces arranged in parallel along a second direction perpendicular to the first direction, one of the plurality of parallel core pieces is a first middle core piece disposed inside the coil, one of the plurality of parallel core pieces is a first side core piece disposed outside the coil, the second core piece has a second middle core piece disposed inside the coil, the first middle core piece has a first surface and a second surface facing each other in a third direction perpendicular to both the first and second directions, and a first end surface connected to the first surface and the second surface and facing the second middle core piece, the second middle core piece has a second end surface facing the first middle core piece, and the first end surface is A reactor having a non-contact portion spaced apart from the second end face, and two protruding portions or four projecting portions projecting from the non-contact portion toward the second end face so as to be in contact with the second end face, wherein the two protruding portions are spaced apart from each other in the second direction and are provided extending from the first surface to the second surface, and the four projecting portions have two first projecting portions spaced apart from each other in the second direction near the first surface, and two second projecting portions spaced apart from each other in the second direction near the second surface, and the gap portion has a middle gap portion provided between the non-contact portion and the second end face.

2. The reactor according to claim 1, wherein the first core piece has an E-shape when viewed from the third direction, the second core piece has a T-shape when viewed from the third direction, the first core piece has a first end core portion arranged facing the first end face of the coil so as to connect the plurality of parallel core portions, the second core piece has a second end core portion arranged facing the second end face of the coil so as to connect to the second middle core portion, the plurality of parallel core portions have a second side core portion arranged outside the coil on the opposite side of the first middle core portion from the first side core portion, and the gap portion has a side gap portion provided between each of the first side core portion and the second side core portion and the second end core portion.

3. The reactor according to claim 2, wherein the first core piece comprises a low-μ portion having a relatively low relative permeability and a high-μ portion having a relatively high relative permeability, the low-μ portion includes two corners formed by the first middle core portion and the first end core portion, the high-μ portion includes a base end portion and a protruding portion, the base end portion extends along the second direction across the axis of the first middle core portion in the first end core portion, and the protruding portion protrudes from the base end portion toward the second middle core portion.

4. The reactor according to claim 3, wherein the base portion is provided along the entire length of the first end core portion in the second direction.

5. The reactor according to claim 3 or claim 4, wherein the relative permeability in the high μ region is 50 or more and 500 or less.

6. The reactor according to any one of claims 3 to 5, wherein the relative permeability in the low μ region is 5 or more and 50 or less.

7. The reactor according to any one of claims 3 to 6, wherein the relative permeability of the second core piece is 50 or more and 500 or less.

8. The reactor according to any one of claims 3 to 7, wherein the high μ portion is composed of a compacted molded body of soft magnetic powder.

9. The reactor according to any one of claims 3 to 8, wherein the low-μ portion is composed of a molded body of a composite material in which soft magnetic powder is dispersed in a resin.

10. The reactor according to any one of claims 1 to 9, wherein the second core piece is composed of a compacted molded body of soft magnetic powder.

11. A converter comprising the reactor described in any one of claims 1 to 10.

12. A power conversion device comprising the converter described in claim 11.

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