JPH05217761A - Magnetic core with gap and inductance element - Google Patents

Abstract

PURPOSE:To uniform the magnetic flux density in the gap and magnetic core so as to prevent the magnetic core from heated due to partial magnetic saturation and to prevent inductance value from decreasing far reducing excess current loss, by providing a gap part with a magnetic substance inclusion layer for making magnetic permeability at the central side larger than that at the peripheral part of the gap part. CONSTITUTION:At a gap part 23, disk-shaped magnetic substance-containing layers 30 and 31 whose relative magnetic permeability is larger than that at a peripheral part 23 are pasted to column-like facing magnetic core parts 9 and 10. By providing with the magnetic substance-containing layers 30 and 31, such relative magnetic permeability distribution as has two stages of relative magnetic permeability is farmed. In short, the relative magnetic permeability at the central side is 4.0 compared with 1.0 at the gap peripheral part 23a. Thus, the gap part 23 is given a relative magnetic permeability distribution, and the part of magnetic flux passing through edge parts 9a and 10a in case with no relative magnetic permeability distribution is attracted toward the inside of the magnetic care by the magnetic substance containing layers 30 and 31, for uniforming magnetic flux within the magnetic core.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic core with a gap and an inductance element (transformer, choke coil, etc.) using this magnetic core.

[0002]

2. Description of the Related Art Conventionally, as a transformer using a magnetic core with a gap, one having a structure shown in FIGS. 8 and 9 is known.

In this transformer, a pair of magnetic core portions 1 and 2 are butted against each other, a gap portion 3 having a predetermined length is formed in the central portion thereof, and a coil portion 4 is arranged around the gap portion. In the central portion of the magnetic core forming the gap portion 3, substantially cylindrical portions 9 and 10 face each other with a predetermined distance.

The magnetic cores 1 and 2 have, for example, a relative magnetic permeability of 1000 to 2000.
Made of ferrite core material with a gap length of 0.6
The magnetic core with a gap (core) 5 can be assembled so as to have a gap portion 3 of mm. FIG. 10 shows an example of the dimensions of the above-mentioned magnetic core portion, for example, 2, but the other magnetic core portion 1 is also the same (however, the unit of the numerical value in the figure is mm: hereinafter the same. ).

In the coil portion 4, a primary coil 6 and a secondary coil 7 are concentrically wound as shown in FIG. 9, and terminals 8 of the respective coils are led out as shown in FIG. There is.

The magnetic core with a gap as described above and the transformer using the magnetic core have the feature that magnetic saturation is less likely to occur as compared with a magnetic core without a gap, but have the following drawbacks. There is.

First, FIG. 11 shows the above-mentioned magnetic core with a gap (the coil portion is omitted). Of the cylindrical facing portions 9 and 10 facing the gap portion 3, hatched lines are shown in the figure. The magnetic flux tends to concentrate on the illustrated annular edge portions 9a and 10a. This situation is shown in Fig. 12 by analysis using magnetic field simulation. Here, "Magna" (Century C
RC Research Center Co., Ltd. was used (the same applies hereinafter).

In this simulation, as shown in FIG. 12, for example, the surface layer region on the gap side of the cylindrical facing portion 10 of the magnetic core 2 is divided into four, and one of them is provided with a larger number of elements 1, 2, 3 ...・ The magnetic flux density B (unit: Tesla T) was calculated for each element by concentrically dividing into 15. Figure the result
The graph is shown in FIG. 12 (however, this result is the same for the remaining divided portions of the magnetic core portion 2 and also for the other magnetic core portion 9).

In the graph of FIG. 12, the horizontal axis represents the magnetic core length direction y.
Is the angle θ, and the vertical axis is the magnetic flux density B (T). The magnetic flux density distributions of the above-mentioned respective elements are shown. According to this, for elements 1 to 15, 1 → 5, 6
B is increasing in the order of → 10, 11 → 15, and B in the 15 part in particular is considerably higher than others. Due to such partial concentration of magnetic flux, a state close to magnetic saturation occurs in that portion, resulting in increased loss and increased heat generation. In addition, the inductance value also decreases.

Further, since the magnetic core with a gap is used,
As compared with the case of a magnetic core without a gap, among the magnetic flux 11 formed in the central portion of the magnetic core as shown in FIG. 13, more leakage magnetic flux 11a is generated between the edge portions 9a-10a. When the degree of leakage of the magnetic flux is large and the magnetic flux crosses the winding (coils 6 and 7 in FIGS. 8 and 9), a spiral electromotive force is generated in the winding by electromagnetic induction, and an eddy current flows. This increases the current flowing through the conductor and increases Joule loss.

FIG. 14 shows the magnitude of the leakage magnetic flux as described above (B (T) is shown by numerical values for each partitioned space area).
Is obtained by the magnetic field analysis described above, and is shown as a vector. According to this, it can be seen that the leakage magnetic flux is large especially near the edge portion 10a of the magnetic core portion 10 and a considerable amount of magnetic flux is leaked even at a position distant from the edge portion.

In order to solve the above problems, an attempt has been proposed to reduce the leakage magnetic flux by making the core shape of the gap portion a special shape, but it is necessary to process or shape the core into a special shape. In addition, there are drawbacks such as an increase in cost. In addition, effective measures to solve the above problems have not yet been proposed.

[0013]

It is an object of the present invention to make the magnetic flux density in the gap portion and the magnetic core uniform in a magnetic core with a gap, and a transformer, a coil and the like using the magnetic core with a gap,
It is intended to prevent heat generation due to partial magnetic saturation of the magnetic core and a reduction in inductance value, and also to reduce eddy current loss by reducing leakage flux.

[0014]

That is, the present invention relates to a magnetic core with a gap configured so that the gap has a distribution of magnetic permeability, and an inductance element such as a transformer or a choke coil using the magnetic core with the gap. Is.

In the present invention, it is desirable that a magnetic substance-containing layer for increasing the magnetic permeability on the central side of the gap portion is provided in the gap portion as compared with the peripheral portion of the gap portion. The magnetic permeability may be curved, linear, or stepwise changed between the portion and the central portion side thereof. In this case, it is particularly desirable that the magnetic permeability be increased from the peripheral portion of the gap portion toward the central portion thereof.

[0016]

EXAMPLES Examples of the present invention will be described below.

1 to 3 show a magnetic core 25 with a gap according to this embodiment, and a transformer using this magnetic core (see FIG. 1).
However, the magnetic core portions 1 and 2 and the coil portion 4, which are the magnetic core body, basically have the same configuration as the conventional example shown in FIGS. Therefore, the same parts as those of the conventional example may be denoted by common reference numerals and the description thereof may be omitted.
The configuration described below is fundamentally different from the conventional example.

That is, in the gap portion 23, its peripheral portion
23a (that is, air or space), the disk-shaped magnetic substance-containing layers 30 and 31 having a relative magnetic permeability larger than that of the columnar opposed magnetic core portion 9
And 10 respectively. In FIG. 2, an example of dimensions of each part is shown for the magnetic core part 2 (unit: mm), but the other magnetic core part 1 is also the same.

The magnetic substance-containing layers 30 and 31 have a relative magnetic permeability of, for example, about 4.0, and the relative magnetic permeability of the gap peripheral portion 23a.
It has a relative magnetic permeability greater than (1.0). For this purpose, for example, a magnetic material having a magnetic permeability of about 100 (for example, Ni-Zn ferrite, molybdenum permalloy) is mixed with a non-magnetic material (for example, synthetic resin), uniformly dispersed, and molded to form a magnetic material. The containing layers 30 and 31 are produced. Alternatively,
Carbonyl iron dust with a relative magnetic permeability of about 4.0 can be selected and molded.

FIG. 4 shows a situation in which the above-mentioned magnetic material-containing layer is provided to form a permeability distribution in which the relative permeability is changed in two steps in the gap portion 23. That is, for the relative permeability (1.0) of the gap peripheral portion 23a (edge portion side),
The relative permeability on the center side (the part near the center of the magnetic core)
It is as large as 4.0.

By giving the distribution of the magnetic permeability to the gap portion 23 in this way, as shown in FIG. 5, a part of the magnetic flux 11a passing through the edge portions 9a and 10a in the conventional example (A) having no magnetic permeability distribution. Is moved in the direction indicated by the broken line by the magnetic substance-containing layers 30 and 31, and the leakage magnetic flux can be attracted to the inside of the magnetic core as shown in (B) to make the magnetic flux density in the magnetic core uniform.

That is, when the magnetic substance-containing layers 30 and 31 are provided, the magnetic flux is more likely to pass through the gap portion on the inner side than on the edge side. Therefore, looking at each magnetic line of force, the magnetic flux passing through the magnetic core and the gap Since the magnetic flux of the portion is connected, a part of the magnetic flux passing through the inner edge portion of the magnetic core can be moved to the inner portion of the magnetic core.

Next, the magnetic core according to the present embodiment was analyzed in the same manner as described above using the magnetic field simulation. However, the length of the gap 23 (distance between the facing portions 9-10) was determined so that the magnetic resistance was equal to that of the magnetic core of the conventional example shown in FIGS. The gap length was changed so as to be the same as that of the conventional example: 0.6 mm in the conventional example, while it was increased to 0.88 mm × 2 = 1.76 mm as shown in FIG. 2). In this way, when the same magnetomotive force is generated, the same amount of total magnetic flux is generated, so that it is possible to purely compare only the distributions of magnetic flux densities. Also,
Having the same magnetic resistance means having the same inductance value.

The result of the magnetic field simulation is shown in FIG. Also here, the magnetic core surface layer region on the gap side is concentrically divided into a large number of elements 1 to 10, and the magnetic flux density B is set for each element.
The magnetic flux density distribution in the magnetic core near the gap was obtained by calculating (T).

According to this result, as compared with that of FIG.
It can be seen that the part where the magnetic flux density was large disappeared and a uniform magnetic flux density distribution without partial concentration of magnetic flux was obtained. Further, among the respective elements, even if B is large, it is significantly reduced as compared with that of FIG. 12, and the variation of B between the maximum and the minimum is also significantly reduced.

FIG. 7 shows, as a vector, the result of magnetic field analysis of the magnitude of the leakage magnetic flux in the magnetic core according to the present embodiment, as described above.

From these results, it can be seen that in the magnetic core of this embodiment, the leakage magnetic flux in the vicinity of the edge portion is greatly reduced as compared with that in FIG.

From the above description, the magnetic core and the transformer according to this embodiment have the following remarkable operational effects. (1) By homogenizing the magnetic flux density in the magnetic core, loss due to partial magnetic saturation, increase in heat generation, and decrease in inductance value can be prevented. (2) By suppressing partial magnetic saturation, the magnetic core as a whole has a margin for magnetic saturation, so that the magnetic core can be reduced as a whole and the transformer can be downsized. (3) By reducing the leakage magnetic flux from the gap, it is possible to reduce the eddy current loss, reduce the loss of the transformer, and improve the efficiency of electronic devices that incorporate them. (4) Since it is only necessary to provide the magnetic substance-containing layer in the gap portion, the magnetic core itself does not need to have any special shape, and the cost can be reduced.

In the embodiments described above, the permeability distribution of the gap portion is set to two levels by the magnetic substance-containing layer, but ideally, the magnetic flux density at the magnetic core edge portion is made more uniform, A smooth permeability distribution curve can be created as shown by the alternate long and short dash line in FIG. This curve is
13 and the magnetic flux density distribution of the edge portion shown in FIG. 5A is estimated to be inversely proportional. That is, in the gap portion, the magnetic permeability μ is decreased on the edge side where the magnetic flux density B is high, and μ is increased on the central portion side where the magnetic flux density B is low. In order to form such a gap material (magnetic substance-containing layer), it is effective to change the degree of dispersion of the magnetic substance in the resin depending on the location.

Further, instead of the above curve, the magnetic permeability may be changed stepwise as shown by the broken line in FIG.

Although the present invention has been described with reference to the embodiments, the above-mentioned embodiments can be further modified based on the technical idea of the present invention.

For example, the profile of the magnetic permeability distribution in the above-mentioned gap portion may be variously changed. In addition to the distribution shown by the one-dot chain line and the broken line in FIG. 4, the magnetic permeability change may be linear, a combination of a straight line and a curved line, or the like.

Regarding the permeability distribution in the gap portion, the relative permeability on the central side where the permeability is larger than that of the peripheral portion needs to be larger than 1.0. Since the change in the magnetic permeability of No. 2 is so rapid that it is undesirable, the upper limit is preferably set to 10.0. It is more desirable that the relative magnetic permeability on the central side is 3.0 to 5.0.

The above-mentioned magnetic substance-containing layer may be a molded product obtained by hardening a magnetic substance with resin, or a molded magnetic substance itself (in this case, the magnetic substance is 100%). Good. The type of magnetic material used is not limited to those described above, and may be appropriately selected from known magnetic materials,
It is also possible to use a mixture of different magnetic materials (for example a mixture of carbonyl iron dust and ferrite).

The means for forming the magnetic permeability distribution in the gap portion is preferably the magnetic substance-containing layer described above, but other means may be adopted.

Further, the shape, structure, material, etc. of the above-mentioned magnetic core can be variously changed. Further, the magnetic core of the present invention can be applied not only to the above-mentioned transformer but also to other inductance elements such as coils (particularly choke coils).

[0037]

As described above, according to the present invention, since the magnetic permeability distribution is provided in the gap portion, the magnetic flux is uniformly formed in the gap portion, whereby the magnetic flux density in the magnetic core is increased. Can be made uniform, and loss due to partial magnetic saturation, increase in heat generation, and decrease in inductance value can be prevented. Further, since the magnetic core as a whole has a margin for the magnetic saturation by suppressing the partial magnetic saturation, the magnetic core can be reduced as a whole, and the inductance element can be downsized. Further, by reducing the leakage magnetic flux from the gap portion, it is possible to reduce the eddy current loss, reduce the loss of the inductance element, and improve the efficiency of the electronic device mounting them.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a magnetic core with a gap and a transformer according to an embodiment of the present invention.

FIG. 2 is a front view and a right side view of a magnetic core portion forming the magnetic core.

FIG. 3 is a perspective view of the magnetic core portion.

FIG. 4 is a distribution diagram of magnetic permeability in a gap portion of the magnetic core.

FIG. 5 is a schematic diagram of a main part for explaining a state of a magnetic flux with and without a magnetic permeability distribution in a gap portion of the same magnetic core.

FIG. 6 is a graph of a gap part of a model and its magnetic flux density distribution when a magnetic flux density distribution is obtained for the same magnetic core by analysis using a magnetic field simulation.

FIG. 7 is a vector diagram of a leakage magnetic flux distribution in the vicinity of a gap obtained by an analysis using a magnetic field simulation for the same magnetic core.

FIG. 8 is an exploded perspective view showing each part of a transformer according to a conventional example separately.

FIG. 9 is a sectional view of the transformer.

FIG. 10 is a front view and a right side view of a magnetic core portion that constitutes a magnetic core of the transformer.

FIG. 11 is a perspective view of the magnetic core.

FIG. 12 is a graph of the gap portion of the model and the magnetic flux density distribution when the magnetic flux density distribution is obtained by analysis using the magnetic field simulation for the magnetic core.

FIG. 13 is a schematic diagram for explaining states of magnetic flux with respect to a magnetic core having no gap and a magnetic core having a gap.

FIG. 14 is a vector diagram of a leakage magnetic flux distribution in the vicinity of a gap obtained by an analysis using a magnetic field simulation for a magnetic core with a gap.

[Explanation of symbols]

 1, 2 Magnetic core part 3, 23 Gap part 4 Coil part 5, 25 Magnetic core 6 Primary coil 7 Secondary coil 9, 10 Opposing magnetic core part 9a, 10a Edge part 11 Magnetic flux 11a Leakage magnetic flux 23a Gap peripheral part 30 , 31 Magnetic substance-containing layer

Claims (6)

[Claims] 1. A magnetic core with a gap configured so that the gap has a distribution of magnetic permeability. 2. The magnetic core with a gap according to claim 1, wherein a magnetic substance-containing layer for increasing the magnetic permeability on the central portion side of the gap portion is provided in the gap portion as compared with the peripheral portion of the gap portion. 3. The magnetic core with a gap according to claim 1, wherein the magnetic permeability changes between the peripheral portion of the gap portion and the central portion side thereof in a curvilinear, linear or stepwise manner. 4. An inductance element using a magnetic core with a gap configured so as to have a distribution of magnetic permeability in the gap portion. 5. The inductance element according to claim 4, wherein a magnetic material-containing layer for increasing the magnetic permeability on the central side of the gap portion is provided in the gap portion as compared with the peripheral portion of the gap portion. 6. The inductance element according to claim 4, wherein the magnetic permeability changes between the peripheral portion of the gap portion and the central portion side thereof in a curvilinear, linear or stepwise manner.