JP2003168614A - Inductor core, inductor and magnetic material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inductor which is improved in current carrying capacity and reduced in power loss in a high-frequency range. <P>SOLUTION: A coil 13, which is wound and extends its ends 13a and 13b in parallel with each other, is housed in a recess 11a surrounded by the peripheral wall 11c of a core 11, and the recess 11a is closed with a plate-like I-shaped core 14 for the formation of an inductor 10. A magnetic leg 12 is provided to the opening 11d of the core 11. The width of the magnetic leg 12 is set equal to that of a gap P between ends 13a and 13b, and the internal surface of the magnetic leg 12 is formed into a curved surface. The magnetic flux of the inductor 10 is set uniform in density by the magnetic leg 12, the required volume of the recess 11a can be ensured by the magnetic leg 12, and the coil 13 can be reduced in DC resistance, so that the inductor 10 can be increased in current carrying capacity and decreased in power loss in a high-frequency region. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inductor core, an inductor, and a magnetic material body capable of achieving both large current and low loss in a high frequency region.

[0002]

2. Description of the Related Art MPs for portable personal computers
There are various types of inductors used in a DC / DC converter that supplies power to a U (Micro Processing Unit). Inductors of recent years are required to have a large current (about 30 A) in order to cope with an increase in current consumption due to an increase in the speed of MPU, and a low loss in a high frequency region (about 300 MHz to 1 GHz) corresponding to the increase in the speed of MPU. Is required. In order to cope with a large current, it is necessary to use a material having a high saturation magnetic flux density for the core forming the inductor, or to form a core shape in which the magnetic flux is less likely to be saturated. On the other hand, in order to reduce the loss in the high frequency region, it is necessary to use a core with low loss in the high frequency region and reduce the DC resistance of the inductor.

FIGS. 15 (a) and 15 (b) show a core 1 called an ER type which constitutes a conventional inductor, and a peripheral wall 1c-1 provided on a pair of opposing sides each having a substantially rectangular shape in plan view. ,
A columnar leg portion 1 is provided at a substantially center of a concave portion 1a surrounded by 1c-2.
b is erected, and the opposite sides of the recess 1a on the side where the peripheral walls 1c-1 and 1c-2 do not exist are openings 1d-1 and 1d-2. An edgewise winding coil 3 shown in FIG. 17 is accommodated in the recessed portion 1a of the core 1, a space 3c at the center of the coil is fitted to the leg 1b, and the terminal portion is used as a terminal by protruding in parallel. Open both ends 3a and 3b with the opening 1d-
It is drawn out from either one of 1 and 1d-2. A magnetic material is used as the material of the core 1.

Further, FIGS. 16A and 16B show another conventional core 1 ', which is called an EP type. The EP type core 1'is provided with a peripheral wall 1c 'which is continuous on three sides and one of which is used as an opening 1d' so that both ends 3a and 3b of the coil 3 housed in the recess 1a 'can be drawn out from the opening 1d'. I have to. In the core 1 ', the inner peripheral side surface 1h' at the central portion of the peripheral wall 1c 'is formed into a curved surface corresponding to the curvature of the outer shape of the coil 3.

In the EP type core 1 ', the coil 3 is surrounded on three sides by a peripheral wall 1c' along the outer shape of the coil 3, which is more direct current than the ER type core 1 shown in FIGS. The magnetic flux density generated when a current is applied is made uniform, and the adaptability to a large current is somewhat improved. To form a core body of an inductor that covers a coil by using the core 1 (or core 1 '), a pair of cores 1 (or a pair of cores 1') are combined in a state of facing each other, or There is a case where the core 1 (or core 1 ') and a plate-shaped core called an I type are combined.

In order to mount the inductor composed of the above-mentioned core 1 or core 1'on a board, a resin with a terminal is used in order to position the inductor and insulate the core on the board mounting side from the terminal of the coil 3. Various bases such as bases,
It is interposed between the core on the board mounting side and the terminal.

[0007]

In the ER type core 1, the magnetic flux density tends to concentrate near the center of the leg portion 1b facing the peripheral walls 1c-1 and 1c-2, which corresponds to a large current. There is a difficult problem. As the material of the core, an Mn—Zn based magnetic material is often used in order to reduce the loss in the high frequency region. However, the Mn—Zn based magnetic material, on the other hand, has a large saturation magnetic flux density, which is large. It is difficult to deal with the current change. Therefore, even when the Mn—Zn based magnetic material is used for the material of the ER type core 1, even if the loss reduction in the high frequency region can be improved, the increase in the current cannot be supported.

In consideration of the above situation, it is possible to assume that the leg portion 1b has a large diameter in order to make the ER type core 1 made of a Mn-Zn magnetic material a large current. However, when the leg 1b has a large diameter, the volume of the recess 1a is reduced, and as a result, the volume of the coil that can be accommodated is also reduced, so that the DC resistance is increased and the Mn—Zn-based magnetic material is used. The improvement in loss reduction is offset somewhat. Therefore, in the current ER type core, it is the actual situation that even if the Mn—Zn based magnetic material is used, it is not possible to satisfy both the increase in current and the reduction in loss in the high frequency region.

On the other hand, although the EP type core 1'has a more uniform magnetic flux density than the ER type core, the presence of the opening 1d 'tends to spread the magnetic flux density in three directions other than the opening 1d'. There is a problem that a uniform magnetic flux density cannot be secured in all four directions, and it is difficult to cope with a large current. Even if the Mn—Zn-based magnetic material is used for the EP type core 1 ′, the situation similar to that of the ER type core 1 falls, and eventually the EP type core 1 ′ has a large current and a low frequency in a high frequency region. It is not possible to achieve both loss and loss.

Further, as shown in FIG. 18, the concave portion 1a '
Since the coil 3 housed in is not positioned in the circumferential direction, the coil 3 is displaced in the circumferential direction. Therefore, as described above, it is necessary to perform positioning using various bases such as a resin base with terminals. There is a problem that assembly is troublesome. This problem also occurs in the ER type coil 1. Further, by using the base, the mounting height of the inductor is increased by the thickness of the base, which is a factor that hinders downsizing of a portable personal computer or the like.

The present invention has been made in order to solve such a problem. By providing a magnetic leg in the opening, the magnetic flux density can be further homogenized and a large current can be dealt with. An object of the present invention is to provide an inductor core, an inductor, and a magnetic material body that reduce direct current resistance and also realize low loss in a high frequency region. Further, according to the present invention, the width of the magnetic leg is set to be the same as the gap between the ends of the coil,
An object of the present invention is to provide an inductor core and an inductor that secure the positioning of the coil in the circumferential direction.

[0012]

According to a first aspect of the present invention, there is provided an inductor core which comprises a recess for accommodating a coil and an opening provided in at least a part of a peripheral wall of the recess. The opening is provided with a magnetic leg that is provided at a distance from the peripheral wall of the recess.

In the inductor core according to the second aspect of the invention, the coil has both ends projecting parallel to each other, and the magnetic leg has a width the same as a gap between both ends of the coil. It is characterized by being. Further, the inductor core according to the third invention is characterized in that the magnetic leg has an inner peripheral surface which is a curved surface corresponding to the outer shape of the coil.

An inductor according to a fourth invention is a coil,
In the inductor having two cores for accommodating the coil, one or both of the two cores are any of the above-described inductor cores. An inductor according to a fifth aspect of the invention includes a coil,
An inductor comprising a first core having a recess for accommodating the coil, an opening provided in at least a part of a peripheral wall of the recess, and a plate-shaped second core closing the recess, The two cores are provided with magnetic legs provided so as to project into the opening at a distance from the peripheral wall of the recess in the closed state of the recess. Further, the inductor according to the sixth aspect of the invention is characterized in that the coil is edgewise wound.

A magnetic material body according to a seventh aspect of the present invention is a magnetic material body having a recess and an opening provided in at least a part of a peripheral wall of the recess, wherein the opening is spaced apart from the peripheral wall of the recess. It is characterized in that it is provided with magnetic legs provided separately. Further, a magnetic material body according to an eighth aspect of the invention is a plate-shaped magnetic material body characterized by including magnetic legs protruding from one surface.

In the first and fourth aspects of the invention, since the magnetic leg is provided in the opening of the inductor core, the generated magnetic flux density can be spread to the opening side by the magnetic leg and the magnetic flux density can be made uniform. As a result, it is possible to cope with a large current. Also, since it is possible to deal with a large current, it is not necessary to make the leg part in the center of the recess a large diameter, and it is possible to secure a concave portion with a required volume, and it is possible to cope with a large current that was difficult in the past and to reduce loss in the high frequency region. Can be compatible with

The magnetic legs can be applied to the openings of both the ER type core and the EP type core. When the magnetic legs are provided on the ER type core, the magnetic legs should be provided on both of the openings. May be. Further, the material of the inductor core according to the present invention is not particularly limited as long as it is a magnetic material, but when an Mn—Zn based magnetic material is used, the degree of adaptability to low loss in a high frequency region is high. Is improved, which is preferable.

In the fourth aspect of the invention, when cores having recesses are combined to form a core body of an inductor, two cores having the same shape and having magnetic legs may be used. One having a magnetic leg may be used for one core and a core having no magnetic leg may be used for the other core. In the latter case, it is preferable to set the height of the magnetic leg provided on one of the cores so that the magnetic core can reach the other core when the cores are combined.

In the second aspect of the invention, since the width of the magnetic leg is the same as the gap between both ends of the coil, once the coil is housed in the recess of the inductor core, the both ends sandwich the magnetic leg. Therefore, the displacement of the coil in the circumferential direction is prevented, and the positioning in the circumferential direction can be secured. As a result, the labor and the like for the coil alignment becomes unnecessary, and the assemblability of the inductor can be improved. Furthermore, since the end of the coil can be used as a terminal, the positioning base that was conventionally interposed between the core and the terminal can be omitted, and the height of mounting on the board can be kept low. As a result, it can contribute to the improvement of the internal layout of a portable personal computer to which the inductor is applied. When the base is omitted, it is necessary to use a Ni—Zn based magnetic material as the material of the core on the substrate side from the viewpoint of insulation between the core and the terminal at the coil end.

The width of the magnetic leg in the second aspect of the invention is set to be the same as that of both ends of the coil, so that the width of the magnetic leg includes a clearance dimension range in which the magnetic leg can be accommodated between the both ends. This means that the dimensions are the same. That is,
With the exact same size, it is very difficult to position the magnetic leg in the gap between both ends of the coil, so when the coil is housed in the recess of the inductor core, the magnetic leg fits smoothly between both ends. As described above, it means that the width of the magnetic leg is set to such a dimension that either one or both of the ends in the width direction of the magnetic leg gently contacts the both ends.

According to the third aspect of the present invention, by making the inner peripheral surface of the magnetic leg a curved surface, the magnetic leg can be covered along the outer shape of the coil. Particularly, in the core provided with the magnetic leg on the EP type base. The entire circumference of the coil can be covered along the outer shape of the coil, the magnetic flux density can be further homogenized, and the accommodation of the coil can be improved.

According to the fifth aspect of the invention, when the inductor is composed of the first core having the concave portion and the plate-shaped second core, the magnetic legs are provided on the plate-shaped second core to provide a uniform magnetic flux density. And reduction of DC resistance can be achieved. According to the sixth aspect of the invention, since the coil is edgewise wound, the height of the coil can be reduced, and an inductor having a size suitable for a portable personal computer or the like can be configured.
Further, by using the edgewise winding coil, the space factor of the coil can be increased, and the conductor resistance can be sufficiently lowered to easily cope with a large current.

In the seventh and eighth inventions, by providing the magnetic legs on the magnetic material body, it is possible to make the magnetic flux density uniform when the magnetic material body is used for an inductor or the like.
DC resistance can also be reduced. In addition, the material of the magnetic material body,
Various magnetic materials such as Mn-Zn system and Ni-Zn system can be applied.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the drawings showing the embodiments thereof. FIG. 1 is an exploded perspective view of the inductor according to the first embodiment of the present invention. The inductor 10 of the first embodiment accommodates the edgewise winding coil 13 in the recess 11a of the core 11 of the first embodiment, which is improved on the basis of the EP type core shape, and also has a plate shape which is an I type core. The I-core 14 closes the recess 11a of the core 11, and the I-core 14 is attached with an auxiliary terminal 15 having an inverted L-shaped cross section.

The I-core 14 is provided with notches 14b and 14c for fitting the parallel protruding ends 13a and 13b of the coil 13 on one side 14a, and the center of the other side 14d facing the one side 14a. A notch 14e for mounting the auxiliary terminal 15 is provided. As the material of the I core 14, a Ni—Zn based magnetic material having high electrical insulation is used. Also, the coil 13 is ring-shaped with a space 13c formed in the center, and insulates the end portions 13a, 13b other than the bent end portions at right angles with enamel or the like, and allows the non-coated end portions to be conductively connected. It has the terminal that was

As shown in FIGS. 2 (a) and 2 (b), the core 11 has a substantially rectangular shape in plan view, and the peripheral wall 11 is continuous with three sides.
A cylindrical leg 11b is formed in the approximate center of the recess 11a surrounded by c.
Is provided upright, and the side of the recess 11a on the side where the peripheral wall 11c does not exist serves as the opening 11d.

At the center of the opening 11d, a magnetic leg 12 is erected at a distance from the peripheral wall 11c to secure a space for arranging the ends 13a and 13b of the coil 13. Magnetic leg 12
Has the same height as that of the peripheral wall 11c, and the width dimension W along the side direction is defined by the respective end portions 13a of the coil 13 shown in FIG.
The size is set to be the same as the clearance P of 13b, and the inner peripheral surface 12
A is formed by a curved surface corresponding to the outer shape of the coil 13. The core 11 is made of Mn—Zn magnetic material, and the central leg 11b is set to have a standard diameter compared to the size of the core 11 itself, and the recess 11a is A sufficient coil storage space is secured.

FIG. 3 shows the coil 1 in the recess 11a of the core 11.
3 shows a state in which 3 is accommodated. The coil 13 is housed in such a manner that the central space portion 13c is fitted into the leg portion 11b and the magnetic leg 12 is sandwiched by both end portions 13a and 13b. Since the width dimension W of the magnetic leg 12 is the same as the gap P between the end portions 13a and 13b, the coil 13 is once
When housed in a, the magnetic legs 12 are positioned in the circumferential direction.

With the coil 13 housed in the recess 11a of the core 11 as described above, as shown in FIG.
4 is covered on the core 11 to close the recess 11a to form a core body. When combining the I core 14, the coil 13
Is positioned, the cutout 14 of the I-core 14
The ends 13a and 13b of the coil 13 can be easily fitted in the coils b and 14c. Further, as shown in FIG. 4A, after the I core 14 is bonded and integrated with the core 11 with the auxiliary terminal 15 attached, each end portion 1 of the coil 13 is
The inductor 10 is completed by refracting 3a and 13b along the outer surface 14f of the I core 14.

Inductor 10 completed as described above
4 is mounted on the board K with the I core 14 side facing the board K side, as shown in FIG. At this time, since the ends 13a and 13b of the coil 13 are positioned by the magnetic legs 12 of the core 11, the inductor 10 can be easily positioned on the substrate K. Moreover, since the inductor 10 can be stably mounted on the substrate K by the terminals of the respective end portions 13a and 13b of the coil 13 and the auxiliary terminal 15,
No base is interposed between the inductor 10 and the substrate K, and the mounting height is kept lower than in the conventional case. In addition,
Even if the base is omitted in this way, the Ni-Z
Since the I core 14 made of the n-based magnetic material is arranged,
Insulation between the I core 14 and the terminals of the ends 13a and 13b of the coil 13 is also ensured.

Further, the magnetic flux density of the inductor 10 is made uniform by the existence of the magnetic legs 12 as compared with the conventional inductor using the EP type core. Specifically, the opening 11d
On the side, the magnetic flux density goes to the magnetic leg 12, so that the degree of concentration of the magnetic flux density is relaxed. By making the magnetic flux density uniform in this way, the magnetic flux is less likely to be saturated, and it is possible to cope with a large current. Further, since the leg portion 11b of the core 11 has a standard diameter dimension, the coil 13 having a required dimension can be accommodated, and in addition to using the Mn—Zn based magnetic material as the core material, the direct current resistance is reduced and in the high frequency region. It also supports low loss.

The inductor 10 and the core 11 of the first embodiment are not limited to the above-mentioned forms, and various modifications can be applied. For example, the inner peripheral surface 12a of the magnetic leg 12 may be formed as a flat surface instead of a curved surface.
Various shapes such as a cylindrical shape and a prismatic shape can be applied. Further, the width of the magnetic leg 12 does not necessarily have to be set to the same size as the gap P between the ends 13a and 13b of the coil 13,
If the positioning of the coil 13 in the circumferential direction is not required, the size may be set smaller than the gap P.

Further, as shown in FIG. 5A, from one side 14a 'sandwiched by the notches 14b' and 14c 'on one surface of one plate-shaped I core 14' forming the core body. You may make it provide the protrusion magnetic leg 16 'equivalent to the above-mentioned magnetic leg 12 which protrudes. In this case, as shown in FIG. 5B, the EP type core 1'shown in FIGS. 16A and 16B is applied to the other core, and the I core 14 'and the core 1'are combined, A projecting magnetic leg 16 'is arranged in the opening 1d' of the core 1'in a state of being spaced from the peripheral wall 1c 'of the recess 1a' to form a core body, and the magnetic flux density is made uniform by the projecting magnetic leg 16 '. Also, it is designed to cope with low loss in the high frequency region.

Further, as shown in FIG. 6, a magnetic leg 12 'having a height corresponding to a part of the magnetic leg 12 of FIG. 2 is provided in the opening 11d' of the core 11 ', and an I core 14 "is provided. Side 1
4a ″ may be provided with a protruding magnetic leg 16 ″ having a height corresponding to the remaining portion of the magnetic leg 12 to form a core body. When the core 11 ′ and the I core 14 ″ are combined, the magnetic legs 12 ′ of the core 11 ′ and the protruding magnetic legs 16 ″ of the I core 14 ″ are brought into contact with each other to be integrated.
The 2'and the protruding magnetic leg 16 "correspond to uniform magnetic flux density and low loss in the high frequency region.

Further, in the case where the core body of the inductor is formed by combining the cores having the concave portions with each other, as shown in FIG.
As shown in FIG. 2A, a pair of cores 11 shown in FIGS. 2A and 2B may be used. Also in this case, since the magnetic legs 12 are respectively present in the openings 11d of the pair of cores 11, it is possible to make the magnetic flux density uniform and reduce the loss in the high frequency region.

Furthermore, as shown in FIG. 7B,
One of the two cores 11 ″ has a height of the magnetic leg 12 ″ that is equal to the height of the magnetic leg 12 of the core 11 of FIGS. 2 (a) and 2 (b).
16a is set on the other core while the double core is set.
You may make it comprise a core body using EP type core 1'of (b). Also in this case, the openings 1d 'and 11
The magnetic leg 12 "is arranged at d", so that the magnetic flux density can be made uniform and the loss can be reduced in the high frequency region.

Moreover, as the auxiliary terminal 15, in addition to the inverted L-shaped cross section shown in FIG. 1, an auxiliary terminal 55 having a U-shaped cross section as shown in FIG. 8A can be used. is there. When using the U-shaped auxiliary terminal 55, in order to avoid interference, it is necessary to provide a groove 54f continuous with the cutout 54e of the I core 54, as shown in FIG. 8B. Further, as shown in FIG. 8C, when the width of the space 55a 'inside the U-shaped auxiliary terminal 55' is equal to the thickness of the I core 54 ', the notch 54e' of the I core 54 '. It is necessary to provide a groove portion 51f 'on the upper end of the peripheral wall 51c' of the core 51 ', which is a portion opposed to.

Next, in order to confirm how the magnetic flux density changes by providing a magnetic leg on the core, the applicant of the present invention has shown in FIGS. 2 (a) (b) according to the first embodiment of the present invention. Experiment 1 in which the core 11 and the EP type core shown in) are compared, and Experiment 2 in which the core 11 and the ER type core are compared.

In Experiment 1, comparisons are made by computer simulation. First, a computer creates a model in which the core 11 and the EP type core are divided into two at each opening, and is shown in FIG. 9 (a). As described above, the peripheral wall 11c, the leg portions 11b, and the magnetic legs 12 of the model corresponding to the core 11 were divided into a lattice shape in plan view to form a large number of blocks h1 to m1. Further, as shown in FIG. 9B, even on the bottom surface side of the core 11, the entire bottom surface is divided into a lattice shape in a form substantially similar to the plan view side, and a large number of blocks a1 to g6 are formed.

On the other hand, also in the model of the EP type core, similar to the core 11 described above, the plan view side and the bottom view side are divided into a lattice shape to form a large number of blocks a1 to l6. In addition, E
Unlike the core 11, the P-type core does not have a magnetic leg, so that the block m1 corresponding to the magnetic leg is not provided. The core 11 and the EP-type core have the same size at each location in order to have the same condition except for the presence or absence of the magnetic leg, and the accommodated coils have the same size with the number of turns of 3T. Was applied and the L value (inductance value) of both unloaded magnets was set to 0.7 μH.

The magnetic flux density when a direct current of 30 amperes was applied to both of the above (Idc = 30 A) was calculated by simulation, and the calculation results are shown in Tables 1 and 2 and the magnetic flux density (mT) for each block. Figure 10
The graphs of (a) and (b) are shown. In addition, Table 1 and FIG.
The graph of (a) is for the plan view side, and the graph of Table 2 and FIG. 10 (b) is for the bottom view side.

[0042]

[Table 1]

[0043]

[Table 2]

From Tables 1 and 2 and FIGS. 10 (a) and 10 (b), the magnetic flux density of the model of the core 11 is lower than that of the EP type core model. It was found that the magnetic flux density of the 11th model was made more uniform than that of the EP type model. For details, see FIG.
In (a), over the blocks 11 to 16 (m1) corresponding to the peripheral wall 11c, the model of the core 11 (core of the present invention) has a magnetic flux density of EP type model (E).
The decrease was remarkable with respect to the P-type core).

Also in FIG. 10B, the magnetic flux density of the model of the core 11 is lower than that of the EP type core over the blocks g1 to g6 corresponding to the back surface of the peripheral wall 11c. At f7, the magnetic flux density of the core 11 model was significantly lower than that of the EP core model. This decrease in the magnetic flux density of the block f7 corresponds to a position between the magnetic leg 12 and the peripheral wall 11c in the model of the core 11 where the block f7 is located, and it is considered that the magnetic leg 12 is provided.

Further, on the bottom view side of FIG. 10B, the amplitude of the magnetic flux density of the model of the core 11 is small and uniform with respect to the model of the EP type core over the blocks d6 to e1 and the blocks e6 to f1. It was confirmed that it has been converted. That is, blocks d6 to d8 and blocks e6 to e8
Is located on the side of the opening of the peripheral wall 11c, while the blocks e1 and f1 are located on the side of the peripheral wall that is substantially opposed to the side of the opening. It was found that the magnetic flux density was made uniform. This means that the core 11 has a magnetic leg 1 on the opening side.
Since 2 is located, it is considered that the same peripheral wall condition as that of the opposing position could be formed.

Experiment 2 is also compared by simulation by a computer, and similarly to Experiment 1, a model in which the core 11 and the ER type core are divided into two at each opening by the computer is prepared. With respect to each of these models, the change in the magnetic flux density was calculated by a computer, the numerical value of each magnetic flux density was divided into 5 stages (A to E), and the distribution of each stage was visually displayed.

The material of each model for the core 11 and the ER type core is Mn- with a saturation magnetic flux density of 590 mT.
Using a Zn-based magnetic material, the side on the opening side is 13.2 mm,
The side orthogonal to the side is 13 mm, and the bottom thickness of the recess is 1.3 mm.
A model of each core was created in mm, and both had an inductance value of 0.9 μH under no load.

FIG. 11A shows the magnetic flux density distribution on the bottom side of the model of the core 11, and FIG. 11B shows the magnetic flux density distribution on the bottom side of the model of the ER type core. , A has the highest magnetic flux density, and thereafter B,
The magnetic flux density decreases in the regions indicated by C and D, and the magnetic flux density decreases in the region indicated by E. Therefore, in the model of the core 11 according to the present invention, the area A having the highest magnetic flux density is not generated, and the area D having the lowest magnetic flux density is evenly distributed over the entire periphery as compared with the ER type core. It was confirmed that it was distributed over a wide range. Therefore, the core 11 is
It was confirmed that the magnetic flux density was made uniform from the R-type core.

Further, in the experiment 3, the present applicant compared the core 11 shown in FIG. 1 with an ER type core having a large diameter at the center leg, in terms of DC superposition characteristics and DC resistance. Both were set to the same size, and Mn—Zn based magnetic materials were used for both core materials. Regarding the DC superposition characteristics, a graph of the inductance reduction rate (ΔL / L) with respect to the applied DC current value (A) is shown in FIG. Further, the DC resistance was found to be 1.4 mΩ for the core 11 type and 2.2 mΩ for the ER type core by measurement.

As shown in FIG. 12, the DC superimposition characteristics show no significant difference in the range of the applied DC current value of about 30 A or less. However, when the applied DC current value exceeds about 30 A, the inductance reduction rate of the ER type core is decreased. It was confirmed that the change was larger. It was also confirmed that the value of the DC resistance was reduced by about 30% in the core 11 as compared with the ER type core, as described above. Therefore, it was found that the core 11 can cope with a large current since the recess 11a secures a required volume and reduces the DC resistance value.

FIG. 13 is an exploded perspective view of the inductor according to the second embodiment of the present invention. In the inductor 20 according to the second embodiment, the edgewise winding coil 23 is vertically sandwiched by two cores 21 based on the ER type, and the coil 23 is housed in each recess 21a.

In the core 21, a leg portion 21b is erected at the center of a recess 21a surrounded by peripheral walls 21c-1 and 21c-2 provided on a pair of opposing sides to form peripheral walls 21c-1 and 21c-.
Two sides on the side where 2 is not provided are openings 21d-1 and 21d.
-2. A magnetic leg 22 equivalent to the magnetic leg 12 of the first embodiment is provided in one opening 21d-1. The height of the magnetic leg 12 is set to the same dimension as the peripheral walls 21c-1 and 21c-2.

By forming the core body by combining the above-mentioned cores 21 in a facing state, the openings 2 of each core 21 are formed.
The central portion of 1d-1 is closed by the magnetic leg 22, so that the magnetic leg 22 makes the magnetic flux density more uniform than the core body formed of the ER type core, and the DC resistance of the inductor 20 is also reduced. I have to.

In the inductor core according to the second embodiment, the magnetic leg 22 can be deformed into various shapes similarly to the magnetic leg 12 of the first embodiment. In addition, the core body can be modified in various ways other than the above-described form.
The core body may be configured by combining cores provided with magnetic legs in both openings, respectively.
As shown in (a), the height of the magnetic leg 22 'of one core 21' is set to be twice as high as that of the magnetic leg 22 of FIG. ) (B) The ER type core 1 may be applied to form a core body.

Further, as shown in FIG. 14 (b), the core 21 'of the modified example is in a state where the projecting sides of the magnetic legs 22' are openings 21d-1 'and 21d-2' which are opposite to each other. In combination, the central portions of the openings 21d-1 'and 21d-2' on both sides may be closed by magnetic legs 22 '.

Furthermore, also in the inductor of the second embodiment, one of the cores is the core 21 of FIG. 13 or a core having magnetic legs in both openings, and the other core is used. It is also possible to form a core body by applying a plate-shaped I core as shown in FIG.

[0058]

According to the inductor core of the first aspect of the invention and the inductor of the fourth aspect of the invention, since the magnetic leg is provided in the opening of the inductor core, the magnetic flux density can be made uniform by the magnetic leg, and the concave portion Since it is not necessary to increase the diameter of the leg portion and the concave portion having a required volume can be secured, both a large current and a low loss in a high frequency region can be achieved.

Further, according to the inductor core of the second invention, the width of the magnetic leg is the same as the gap between both ends of the coil, so that the coil can be positioned in the circumferential direction, and as a result, the position of the coil is aligned. Therefore, the efficiency of inductor assembly can be improved, and the cost of the inductor can be reduced. Furthermore, according to the inductor core of the third invention,
By making the inner peripheral surface of the magnetic leg a curved surface, the magnetic flux density can be made more uniform by substantially enclosing the entire circumference of the coil.

According to the inductor of the fifth aspect of the invention, even when the core having the recessed portion and the plate-like core is formed,
By providing the magnetic legs on the plate-shaped core, it is possible to make the magnetic flux density uniform and reduce the DC resistance. Further, according to the inductor of the sixth invention, by using the coil of edgewise winding, the height of the inductor can be reduced and the space factor of the coil can be improved, and further, the conductor resistance can be sufficiently reduced to increase the large current. It is possible to further improve the degree of adaptability.

Further, according to the magnetic material bodies of the seventh and eighth inventions, since each magnetic material body is provided with the wall portion, when such each magnetic material body is used for an inductor or the like, a large current is generated. It is possible to provide an inductor and the like that can cope with higher cost and lower loss in the high frequency region.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of an inductor according to a first embodiment of the present invention.

FIG. 2 is an inductor core according to the first embodiment,
(A) is a plan view and (b) is a sectional view taken along line XX of (a).

FIG. 3 is a plan view showing a state where a coil is housed in the inductor core of the first embodiment.

FIG. 4A is a schematic view of a state in which a core body of the inductor core of the first embodiment is formed, and FIG. 4B is a schematic view of a state in which the inductor is mounted on a substrate.

FIG. 5A is a perspective view of an I core according to a modification of the first embodiment, and FIG. 5B is a schematic cross-sectional view of a core body formed using the I core of the modification.

FIG. 6 is a schematic cross-sectional view when forming a core body of another modification example according to the first embodiment.

7A is a schematic cross-sectional view when a core body is formed by using two cores according to the first embodiment, and FIG. 7B is a core of another modification according to the first embodiment. FIG. 6 is a schematic cross-sectional view of a case where a core body is formed by using the and EP type cores.

FIG. 8 is a modification of the auxiliary terminal, (a) is a perspective view,
(B) is the YY sectional view taken on the line of (a), (c) is a schematic sectional drawing of another modification.

FIG. 9 is a block formation state for a core model according to Experiment 1, (a) is a block layout diagram on a plan view side,
(B) is a block layout diagram on the bottom view side.

10A and 10B are graphs showing the magnetic flux density for each block according to Experiment 1, where FIG. 10A is a graph on the plan view side, and FIG.
Is a graph on the bottom side.

11A and 11B show distribution states of magnetic flux densities of a core model according to Experiment 2, where FIG. 11A is a bottom view side magnetic flux density distribution diagram in the core model of the first embodiment, and FIG. It is a distribution diagram of the magnetic flux density on the bottom view side in the model of the core.

FIG. 12 is a graph showing the relationship between the applied DC current value and the inductance reduction rate in Experiment 3.

FIG. 13 is an exploded perspective view of an inductor according to a second embodiment of the present invention.

FIG. 14A is a schematic cross-sectional view when a core body is formed using a core according to a modification of the second embodiment and an EP type core, and FIG. 14B is a modification of the second embodiment. It is a schematic sectional drawing at the time of forming a core body using two such cores.

FIG. 15 is a conventional ER type core, in which (a) is a plan view and (b) is a front view.

FIG. 16 is a conventional EP type core, in which (a) is a plan view and (b) is a front view.

FIG. 17 is a plan view of an edgewise winding coil.

FIG. 18 is a schematic plan view showing one of conventional problems.

[Explanation of symbols]

10 inductor 11 cores 11b legs 11c peripheral wall 11d opening 12 magnetic legs 13 coils 13a, 13b ends 14 I core 15 Auxiliary terminal

Claims (8)

[Claims] 1. An inductor core comprising a recess for accommodating a coil and an opening provided in at least a part of a peripheral wall of the recess, wherein the opening is provided at a distance from the peripheral wall of the recess. An inductor core characterized by having a magnetic leg. 2. The inductor core according to claim 1, wherein both ends of the coil project in parallel, and the magnetic leg has the same width as the gap between both ends of the coil. . 3. The inductor core according to claim 1, wherein an inner peripheral surface of the magnetic leg has a curved surface corresponding to an outer shape of the coil. 4. An inductor comprising a coil and two cores for accommodating the coil, wherein one or both of the two cores are defined in any one of claims 1 to 3. An inductor characterized by being a core for an inductor. 5. A first core having a coil, a recess for accommodating the coil, an opening provided in at least a part of a peripheral wall of the recess, and a plate-shaped second core closing the recess. The inductor according to claim 2, wherein the second core includes a magnetic leg provided so as to project into the opening at a distance from a peripheral wall of the recess when the recess is closed. 6. The inductor according to claim 4, wherein the coil is edgewise wound. 7. A magnetic material body comprising a recess and an opening provided in at least a part of a peripheral wall of the recess, wherein a magnetic leg provided in the opening at a distance from the peripheral wall of the recess. A magnetic material body characterized by comprising. 8. A plate-shaped magnetic material body, comprising magnetic legs protruding from one surface.