JP2002175918A - Inductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inductor, the permanent magnets of which are not demagnetized, because the inductor can maintain a high magnetic inductance value, even if the electrical current supplied to the inductor has a large value and hardly causes eddy current loses and abnormal current heat generation, and in addition, which can obtain a stronger magnetic bias effect, with non increase in size. SOLUTION: This inductor is constituted by winding a coil 22 around the core edge of a magnetic core 21 having magnetic gaps G and fitting permanent magnets 23 to the core 21 to face the gaps G. Each permanent magnet 23 has a shape such that the dimension parallel to a magnetic path formed in the core 21 or its tangential line on the cross section of the magnet 23 cut in parallel with the fitting surface of the magnet 23 to the core 21 becomes larger as approaching the core 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic element having a coil wound around a magnetic core, and more particularly, to an inductor and a transformer used in various electronic devices and power supplies for reducing core loss by using a DC bias. About.

[0002]

2. Description of the Related Art In recent years, various electronic devices have been reduced in size and weight. Accordingly, the relative volume ratio of the power supply unit to the entire electronic device tends to increase. This is because it is difficult to reduce the size of magnetic components such as inductors and transformers, which are indispensable for the circuit elements of the power supply unit, while various circuits are implemented as LSIs. Various methods have been tried.

In order to reduce the size and weight of magnetic elements such as inductors and transformers (hereinafter collectively referred to as inductors), it is effective to reduce the volume of a magnetic core made of a magnetic material. Generally, when the size of the core is reduced, the magnetic core is likely to be magnetically saturated, so that there is a problem in that the current value that can be handled as a power source is reduced. As a measure for solving this problem, a technique is known in which a magnetic gap (gap) is provided in a part of the magnetic core to increase the magnetic resistance of the magnetic core and prevent the current value from decreasing. However, in this case, the magnetic inductance of these magnetic components decreases.

As a method for preventing the magnetic inductance from decreasing, for example, Japanese Patent Application Laid-Open No. H01-169905 describes a technique relating to the structure of a magnetic core using a permanent magnet for generating a magnetic bias. In this technique, a direct current magnetic bias is applied to a magnetic core using a permanent magnet, and as a result, the number of lines of magnetic force that can pass through a magnetic gap is increased. However, since the magnetic flux generated by the coil wound around the magnetic core passes through the permanent magnet in the magnetic gap, there is a problem that the permanent magnet is demagnetized due to eddy current loss or abnormal current heating. In addition, there is a problem that the smaller the shape of the permanent magnet inserted into the magnetic air gap, the greater the effect of demagnetization due to external factors.

Therefore, there is a demand for an inductor having a small magnetic core volume, in which the shape of the permanent magnet to be mounted is less limited and the permanent magnet is not demagnetized by the magnetic flux generated by the coil wound around the magnetic core. I have. In order to realize such an inductor, for example, Japanese Patent Application Laid-Open No. 08-316
No. 049 discloses a magnetic core in which two core pieces are opposed to each other via a magnetic gap to form a closed magnetic circuit, a coil wound around at least one of the magnetic cores, In an inductor having a permanent magnet for bias provided on a core, the permanent magnet is placed on the outer surface of the magnetic core so that a bias magnetic flux generated by the permanent magnet and a magnetic flux generated by the coil flow in the magnetic core so as to face each other. Among them, an inductor arranged in a bridge manner on a gap is disclosed.

FIGS. 8A to 8D show a conventional technique of this kind. 8A to 8D, the bobbin 14
The magnetic core 11 is inserted into the coil 12 wound around the coil 12. Further, the permanent magnet 13 is mounted on the gap G on the outer surface of the magnetic core 11 in a cross-linked manner.

The magnetic core 11 in which the permanent magnet 13 is mounted on the gap G in a cross-linked manner maintains a high magnetic inductance value even at a larger current value, as compared with the magnetic core without the permanent magnet 13 mounted. In addition, since the magnetic flux generated by the coil hardly passes through the magnetic path including the permanent magnet 13, eddy current loss and abnormal current heating hardly occur, and therefore, the permanent magnet is not demagnetized.

[0008]

FIG. 8 (a)
To the conventional inductors of this type, including those shown in FIGS.
There is a need for an improvement that can provide a stronger DC bias effect.

Therefore, an object of the present invention is to maintain a high magnetic inductance value even at a large current value, and to prevent eddy current loss and abnormal current heating from occurring, so that the permanent magnet is not demagnetized. Another object of the present invention is to provide an inductor which can obtain a stronger magnetic bias effect without increasing the size of the device.

[0010]

According to the present invention, a coil is wound around a core side of a magnetic core having a magnetic gap,
Further, in the inductor in which a permanent magnet is mounted so as to face the magnetic gap, the permanent magnet is formed in a magnetic path formed in the magnetic core having a cross section parallel to a mounting surface to the magnetic core or a tangent line thereof. An inductor is obtained, which has a shape in which the parallel dimension increases as approaching the magnetic core.

According to the present invention, the permanent magnet is a resin having a specific coercive force of 10 KOe or more and a Tc of 500 ° C. or more, and a volume ratio of a rare earth magnet powder having a powder average particle diameter of 2.5 to 50 μm of 30% or more. And the inductor is a bonded magnet having a specific resistance of 1 Ωcm or more.

According to the present invention, the magnetic core is made of MnZ.
The inductor made of n-based or NiZn-based ferrite, silicon steel plate, or amorphous is obtained.

[0013]

In the inductor according to the present invention, the permanent magnet mounted so as to face the magnetic air gap of the magnetic core is parallel to a magnetic path formed in the magnetic core having a cross section parallel to the mounting surface to the magnetic core or a tangent line thereof. Since the shape is such that the critical dimension increases as it approaches the magnetic core, more magnetic flux from the permanent magnet can be passed through the magnetic core. Thereby, a stronger magnetic bias can be applied, and the output current (power) can be increased as an inductor or a transformer. Further, the size of the permanent magnet required to obtain the same bias (output power) as that of the related art can be made smaller than that of the related art, which is useful for reducing the size, weight, and cost of the entire inductor. It is preferable to use an anisotropic permanent magnet.

On the other hand, in a conventional rectangular parallelepiped permanent magnet,
There is a case where the leakage magnetic flux is relatively large and the demand for obtaining a stronger magnetic bias is not always sufficient.
Further, in order to obtain a stronger magnetic bias with the conventional rectangular parallelepiped permanent magnet, it is necessary to increase the size of the permanent magnet, which is disadvantageous in reducing the size, weight, and cost of the entire inductor.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an inductor according to an embodiment of the present invention will be described with reference to the drawings.

[Embodiment 1] FIGS. 1 (a) to 1 (c)
FIG. 3 is a diagram illustrating a configuration of an inductor according to the present embodiment.

Referring to FIGS. 1A to 1C, in the present inductor, a coil is wound around a core side of a magnetic core 21 made of a soft magnetic material having a magnetic gap G. This is an inductor in which the permanent magnet 23 is mounted so as to face the gap G. In the present inductor, the magnetic core 21 is configured such that two substantially E-shaped core pieces are attached to each other, the respective core side end faces are attached to each other, and the magnetic core 21 is mounted horizontally. The present inductor further includes a base 24 serving as a bobbin on which the coil 22 is wound and a terminal 25 to which the winding end of the coil 22 is electrically connected is implanted.
have.

The two permanent magnets 23 face the gap G and include the base 24, the magnetic core 21, and the coil 22, while excluding the permanent magnets 23. It is installed in an empty space within the maximum outer shape.

The permanent magnet 23 has a magnetic path formed in the magnetic core 21 having a cross section parallel to the mounting surface on the magnetic core 21 or a dimension parallel to a tangent line of the magnetic path increases as the magnetic core 21 approaches. It has a shape. This allows more magnetic flux from the permanent magnet 23 to pass through the magnetic core 21. Therefore, a stronger magnetic bias can be applied, and the output current (power) can be increased as an inductor or a transformer. Further, the size of the permanent magnet 23 required to obtain the same bias (output power) as that of the related art can be made smaller than that of the related art, which is useful for reducing the size, weight, and cost of the entire inductor.

The magnetic core 21 is made of Mn-Zn ferrite, has a magnetic permeability of 4 × 10 ⁻³ H / m, and a magnetic path length of 0.1 × 10 ⁻³ H / m.
02 m, and the effective area is 5 × 10 ⁻⁶ m ² .

On the other hand, the permanent magnet 23 is a sintered Ba-based ferrite magnet and has a characteristic that the coercive force is 100 A / m or more and the residual magnetic flux density is 0.4 T.

FIG. 7 shows the DC superposition characteristics of the inductor shown in FIG. 1 and an inductor having the same configuration as that of FIG. 1 except that no permanent magnet 23 is used as a comparative example. As is clear from FIG. 7, the present inductor having the permanent magnet 23 is superior to the inductor having no permanent magnet in DC superposition characteristics.

More specifically, as the permanent magnet 23,
As a result of the examination, the specific coercive force was 10 KOe or more and Tc was 5
A bonded magnet having a volume ratio of a rare earth magnet powder having a powder average particle diameter of at least 00 ° C. of 2.5 to 50 μm of 30% or more and a specific resistance of 1 Ωcm or more is preferable.

More preferably, the composition of the rare earth alloy is S
_{m (Co bal. Fe 0.15-0 .25} Cu
_0.05-0.06 Zr _0.02-0.03 )
_7.0-8.5 , and the type of resin used for the bonded magnet is any of polyimide resin, epoxy resin, polyphenylsulfite resin, silicone resin, polyester resin, aromatic nylon, and chemical polymer. ,
The rare earth magnet powder contains a silane coupling material and a titanium coupling material.

In order to obtain higher characteristics, the bond magnet is made anisotropic by magnetic field orientation at the time of production, and the magnetizing magnetic field of the bond magnet is set to 2.5 T or more and magnetized after assembly. It has been discovered that an excellent DC superposition characteristic can be obtained, and that a magnetic core without deterioration of the core loss characteristic can be formed. This is because the magnet characteristics necessary for obtaining excellent DC superposition characteristics are not the energy product but the intrinsic coercive force, and therefore, even if a permanent magnet having a high specific resistance is used, the intrinsic coercive force is high. For example, it has been found that a sufficiently high DC superimposition characteristic can be obtained.

A magnet having a high specific resistance and a high specific coercive force can be generally obtained by a rare earth bonded magnet formed by mixing a rare earth magnet powder with a binder, but if the magnet powder has a high coercive force, Any composition is possible. The type of rare earth magnet powder is SmCo type,
Although there are NdFeB type and SmFeN type, considering the reflow conditions and oxidation resistance, a magnet having a Tc of 500 ° C. or more and a coercive force of 10 KOe or more is required.
Limited to 2Co17-based magnets.

As the magnetic core for the choke coil and the transformer, any material having a soft magnetic property is effective.
iZn-based ferrite, dust core, silicon steel plate, amorphous and the like are used.

There is no particular limitation on the shape of the magnetic core 21, and the shape of the magnetic core 21 is not particularly limited.
The present invention can be applied to a magnetic core having any shape such as an EI core.

A gap G is provided in at least one or more of the magnetic paths of these cores, and a permanent magnet 23 is mounted so as to face the gap G and in an empty space RS within the maximum outer shape of the inductor.

There is no particular limitation on the gap length. If the gap length is too narrow, the DC superposition characteristics deteriorate, and if the gap length is too wide, the magnetic permeability is too low, so the gap length to be inserted naturally is determined. .

The required characteristics of the permanent magnet 23 are as follows. With respect to the intrinsic coercive force, if the coercive force is less than 10 KOe, the coercive force disappears due to the DC magnetic field applied to the magnetic core. The larger the value, the better, but if it is 1 Ω · cm or more, it does not become a major factor in core loss deterioration. When the average maximum particle size of the powder is 50 μm or more, the core loss characteristics deteriorate. Therefore, the maximum particle size of the powder is desirably 50 μm or less, and the minimum particle size is 2.
If the particle size is 5 μm or less, the decrease in magnetization due to the oxidation of the powder during powder heat treatment and reflow becomes remarkable, so that a particle size of 2.5 μm or more is required.

Table 1 below shows the characteristics of various soft magnetic materials applicable to the magnetic core 21. Table 2 below shows the characteristics of various hard magnetic materials applicable to the permanent magnet 23.

[0033]

[Table 1]

[0034]

[Table 2]

[Embodiment 2] FIGS. 2 (a) to 2 (e)
FIG. 3 is a diagram illustrating a configuration of an inductor according to the present embodiment.

Referring to FIGS. 2A to 2E, in the present inductor, a coil is wound around a core side of a magnetic core 31 made of a soft magnetic material having a magnetic gap (gap) G. This is an inductor in which the permanent magnet 33 is mounted so as to face the gap G. In the present inductor, the magnetic core 31 is configured such that two substantially E-shaped core pieces are attached to each other, the respective core side end faces are attached to each other, and the magnetic core 31 is mounted horizontally. The present inductor further includes a bobbin base 34 on which a coil 35 is wound and a terminal 35 to which the winding end of the coil 32 is electrically connected is implanted.
have.

The four permanent magnets 33 face the gap G and include the base 34, the magnetic core 31, and the coil 32, while excluding the permanent magnets 33. It is installed in an empty space within the maximum outer shape.

The permanent magnet 33 also has a magnetic path formed in the magnetic core 31 having a cross section parallel to the mounting surface on the magnetic core 31 or a dimension parallel to a tangent line of the magnetic path increases as the magnetic core 31 approaches. It has a shape. This allows more magnetic flux from the permanent magnet 33 to pass through the magnetic core 31. Therefore, a stronger magnetic bias can be applied, and the output current (power) can be increased as an inductor or a transformer. In addition, the size of the permanent magnet 33 required to obtain the same bias (output power) as that of the related art can be made smaller than that of the related art, which is useful for reducing the size, weight, and cost of the entire inductor.

The magnetic core 31 is made of Mn-Zn ferrite, has a magnetic permeability of 4 × 10 ⁻³ H / m, and a magnetic path length of 0.1 × 10 ⁻³ H / m.
02 m, and the effective area is 5 × 10 ⁻⁶ m ² .

On the other hand, the permanent magnet 33 is a sintered Ba-based ferrite magnet, and has characteristics of a coercive force of 100 A / m or more and a residual magnetic flux density of 0.4 T.

[Embodiment 3] FIGS. 3 (a) to 3 (d)
FIG. 3 is a diagram illustrating a configuration of an inductor according to the present embodiment.

Referring to FIGS. 3A to 3D, in the present inductor, a coil is wound around a core side of a magnetic core 41 made of a soft magnetic material having a magnetic air gap (gap) G. This is an inductor in which the permanent magnet 43 is mounted so as to face the gap G. In the present inductor, the magnetic core 41 is configured such that two substantially E-shaped core pieces are attached to each other, the respective core side end faces are attached to each other, and the magnetic core 41 is vertically mounted. Further, the present inductor has a bobbin-based base 44 in which a coil 45 is wound and a terminal 45 to which a winding end of the coil 42 is electrically connected is implanted.
have.

The four permanent magnets 43 face the gap G, and include the base 44, the magnetic core 41, and the coil 42, while excluding the permanent magnets 43. It is installed in an empty space within the maximum outer shape.

The permanent magnet 43 also has a magnetic path formed in the magnetic core 41 having a cross section parallel to the mounting surface on the magnetic core 41 or a dimension parallel to a tangent line of the magnetic path increases as the magnetic core 41 approaches. It has a shape. This allows more magnetic flux from the permanent magnet 43 to pass through the magnetic core 41. Therefore, a stronger magnetic bias can be applied, and the output current (power) can be increased as an inductor or a transformer. Further, the size of the permanent magnet 43 required to obtain the same bias (output power) as that of the related art can be made smaller than that of the related art, which is useful for reducing the size, weight, and cost of the entire inductor.

The magnetic core 41 is made of Mn-Zn ferrite, has a magnetic permeability of 4 × 10 ⁻³ H / m, and a magnetic path length of 0.1 × 10 ⁻³ H / m.
02 m, and the effective area is 5 × 10 ⁻⁶ m ² .

On the other hand, the permanent magnet 43 is a sintered Ba-based ferrite magnet, which has a characteristic that the coercive force is 100 A / m or more and the residual magnetic flux density is 0.4 T.

[Embodiment 4] FIGS. 4 (a) to 4 (d)
FIG. 3 is a diagram illustrating a configuration of an inductor according to the present embodiment.

Referring to FIGS. 4A to 4D, in the present inductor, a coil is wound around a core side of a magnetic core 51 made of a soft magnetic material having a magnetic air gap (gap) G. This is an inductor in which the permanent magnet 53 is mounted so as to face the gap G. In the present inductor, the magnetic core 51 is constituted by two substantially cylindrical core pieces, each end face of which is attached to each other, and furthermore, vertically overlapped, and is also called a pot type. Magnetic core 5
A coil 52 is wound around each of the core pieces in the circumferential direction. Further, the present inductor has a base 54 on which a terminal 55 to which a winding end of a coil 52 is electrically connected is implanted.

The four permanent magnets 53 face the gap G and include the base 54, the magnetic core 51, and the coil 52, while excluding the permanent magnets 53 except for the permanent magnet 53. It is installed in an empty space within the maximum outer shape.

The permanent magnet 53 also has a magnetic path formed in the magnetic core 51 having a cross section parallel to the mounting surface on the magnetic core 51 or a dimension parallel to a tangent line of the magnetic path increases as the magnetic core 51 approaches. It has a shape. This allows more magnetic flux from the permanent magnet 53 to pass through the magnetic core 51. Therefore, a stronger magnetic bias can be applied, and the output current (power) can be increased as an inductor or a transformer. Further, the size of the permanent magnet 53 required to obtain the same bias (output power) as that of the related art can be made smaller than that of the related art, which is useful for reducing the size, weight, and cost of the entire inductor.

The magnetic core 51 is made of Mn-Zn ferrite and has a magnetic permeability of 4 × 10 ⁻³ H / m.

On the other hand, the permanent magnet 53 is a sintered Ba-based ferrite magnet and has characteristics such that the coercive force is 100 A / m or more and the residual magnetic flux density is 0.4 T.

Fifth Embodiment FIGS. 5A to 5D show
FIG. 3 is a diagram illustrating a configuration of an inductor according to the present embodiment.

Referring to FIGS. 5A to 5D, in the present inductor, a coil is wound around a core side of a magnetic core 61 made of a soft magnetic material having a magnetic gap (gap) G. This is an inductor in which the permanent magnet 63 is mounted so as to face the gap G. In the present inductor, the magnetic core 61 is configured such that two substantially U-shaped core pieces are attached to each other, the respective core side end faces are attached to each other, and the magnetic core 61 is vertically mounted. Further, the present inductor has a bobbin 64 around which a coil 62 is wound. Coil 62
Are drawn out of the present inductor as lead terminals.

The two permanent magnets 63 face the gap G and include the bobbin 64, the magnetic core 61, and the coil 62, but exclude the permanent magnets 63. It is installed in an empty space within the maximum outer shape.

The permanent magnet 63 has a magnetic path formed in the magnetic core 61 having a cross section parallel to the mounting surface to the magnetic core 61 or a dimension parallel to a tangent line of the magnetic path increases as the magnetic core 61 approaches. It has a shape. This allows more magnetic flux from the permanent magnet 63 to pass through the magnetic core 61. Therefore, a stronger magnetic bias can be applied, and the output current (power) can be increased as an inductor or a transformer. Further, the size of the permanent magnet 63 required to obtain the same bias (output power) as that of the related art can be made smaller than that of the related art, which is useful for reducing the size, weight, and cost of the entire inductor.

The magnetic core 61 is made of Mn-Zn ferrite and has a shape having a magnetic permeability of 4 × 10 ⁻³ H / m and an effective area of 5 × 10 ⁻⁶ m ² .

On the other hand, the permanent magnet 63 is a sintered Ba-based ferrite magnet and has the characteristics that the coercive force is 100 A / m or more and the residual magnetic flux density is 0.4 T.

[Embodiment 6] FIGS. 6 (a) to 6 (d)
FIG. 3 is a diagram illustrating a configuration of an inductor according to the present embodiment.

Referring to FIGS. 6A to 6D, in the present inductor, a coil is wound around a core side of a magnetic core 71 made of a soft magnetic material having a magnetic gap (gap) G. This is an inductor in which the permanent magnet 73 is mounted so as to face the gap G. In the present inductor, the magnetic core 71 is configured such that two substantially U-shaped core pieces are attached to each other, the respective core side end faces are attached to each other, and the magnetic core 71 is vertically mounted. The present inductor further includes a bobbin-based base 7 on which a coil 75 is wound and a terminal 75 to which the winding end of the coil 72 is electrically connected is implanted.
Four.

The two permanent magnets 73 face the gap G and include a base 74, a magnetic core 71, and a coil 72, while excluding the permanent magnet 73. It is installed in an empty space within the maximum outer shape.

The permanent magnet 73 also has a magnetic path formed in the magnetic core 71 having a cross section parallel to the mounting surface on the magnetic core 71 or a dimension parallel to a tangent line of the magnetic path increases as the magnetic core 71 approaches. It has a shape. This allows more magnetic flux from the permanent magnet 73 to pass through the magnetic core 71. Therefore, a stronger magnetic bias can be applied, and the output current (power) can be increased as an inductor or a transformer. Further, the size of the permanent magnet 73 required to obtain the same bias (output power) as that of the related art can be made smaller than that of the related art, which is useful for reducing the size, weight, and cost of the entire inductor.

The magnetic core 71 is made of Mn-Zn ferrite and has a shape having a magnetic permeability of 4 × 10 ⁻³ H / m and an effective area of 5 × 10 ⁻⁶ m ² .

On the other hand, the permanent magnet 73 is a sintered Ba-based ferrite magnet, which has a characteristic that the coercive force is 100 A / m or more and the residual magnetic flux density is 0.4 T.

[0065]

According to the inductor of the present invention, the permanent magnet mounted so as to face the magnetic gap of the magnetic core has a magnetic path formed in the magnetic core having a cross section parallel to the mounting surface to the magnetic core or a tangent line thereof. The shape parallel to the magnetic core increases as it gets closer to the magnetic core, so it can maintain a high magnetic inductance value even at large current values, and eddy current loss and abnormal current heating are unlikely to occur. In addition to no demagnetization, a stronger magnetic bias effect can be obtained without enlarging the device size. Since the mounting space does not increase,
It is suitable for use in electronic devices for which reduction in thickness and weight is desired.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an inductor according to a first embodiment of the present invention, wherein (a), (b), and (c) are a perspective view, a bottom view, and a side view of the inductor, respectively.

FIG. 2 is a diagram showing a configuration of an inductor according to a second embodiment of the present invention, wherein (a), (b), (c), (d), and (e) are a perspective view and a bottom view of the inductor, respectively. Figure,
It is a front view, a top view, and a side view.

FIG. 3 is a diagram showing a configuration of an inductor according to a third embodiment of the present invention, wherein (a), (b), (c), and (d) are a perspective view, a top view, and a front view of the inductor, respectively. , And a side view.

FIG. 4 is a diagram showing a configuration of an inductor according to a fourth embodiment of the present invention, where (a), (b), (c), and (d) are a perspective view, a top view, and a front view of the inductor, respectively. , And a side view.

FIG. 5 is a diagram showing a configuration of an inductor according to a fifth embodiment of the present invention, wherein (a), (b), (c), and (d) are a perspective view, a top view, and a front view of the inductor, respectively. , And a side view.

FIG. 6 is a diagram showing a configuration of an inductor according to a sixth embodiment of the present invention, wherein (a), (b), (c), and (d) are a perspective view, a top view, and a front view of the inductor, respectively. , And a side view.

FIG. 7 is a diagram showing DC superposition characteristics of the inductor according to the first embodiment of the present invention and a conventional inductor having no permanent magnet as a comparative example.

FIG. 8 is a diagram showing a configuration of a conventional inductor;
(A), (b), (c), and (d) are a perspective view, a top view, a front view, and a side view of the inductor, respectively.

[Description of Signs] 11, 21, 31, 41, 51, 61, 71 Magnetic core 12, 22, 32, 42, 52, 62, 72 Coil 13, 23, 33, 43, 53, 63, 73 Permanent magnet 24 , 34, 44, 54, 74 Base 14, 64 Bobbin 25, 35, 45, 55, 75 Terminal

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H01F 1/34 H01F 21/08 19/08 37/00 A 21/08 R 37/00 1/04 B 1/14 C 38/02 37/02 (72) Inventor Teruhiko Fujiwara 7-7-1, Koriyama, Taishiro-ku, Sendai-shi, Miyagi F-term (reference) 5E040 AA06 AA19 BB03 CA20 NN04 NN06 NN12 NN15 5E041 AA02 AB01 AB02 BD03 5E070 AA01 AB04 BA08 BB01 BB02 BB05 CA12 EA08

Claims (3)

[Claims] 1. An inductor in which a coil is wound around a core side of a magnetic core having a magnetic gap, and a permanent magnet is further attached so as to face the magnetic gap, wherein the permanent magnet is connected to the magnetic core. An inductor having a shape such that a dimension parallel to a magnetic path formed in the magnetic core or a tangent line thereof in a cross section parallel to the mounting surface of the magnetic core increases as approaching the magnetic core. 2. The permanent magnet has a specific coercive force of 10 KO.
e and the average particle size of the powder having a Tc of 500 ° C. or more is 2.5
2. The inductor according to claim 1, wherein the volume ratio of the rare earth magnet powder having a volume of 〜50 μm is made of a resin having a volume ratio of 30% or more, and the specific resistance is 1 Ωcm or more. 3. The magnetic core is made of MnZn or Ni.
3. The inductor according to claim 1, wherein the inductor is made of Zn-based ferrite, silicon steel plate, or amorphous.