JPH04320014A - Choke coil - Google Patents

Abstract

PURPOSE:To provide a choke coil with stable quality at the low cost wherein a leakage magnetic flux due to a gap, that is a problem with prior art choke coils, is reduced and simultaneously noise is also reduced. CONSTITUTION:A title choke coil 3 is characterized in that it comprises a wound iron core 1 yielded by winding an amorphous alloy thin band including a crystallized layer within the thickness of a plate. Use of, as the iron core 1, the amorphous alloy thin band including the crystallized layer within the thickness of the plate eliminates a need of a gap formed in a magnetic path required conventionally, and hence a leakage magnetic flux due to the foregoing gap and hence noise can be reduced. Additionally, the present material is crystallized simultaneously upon the amorphous thin band being fabricated and hence it enjoys a merit that a stable material quality is stably ensured.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a choke coil used for absorbing voltage fluctuations in power lines of electronic equipment, etc.

0002

[Prior Art] A conventional choke coil using a wound iron core uses a grain-oriented silicon steel plate or an amorphous alloy as the material for the iron core, and has a gap 5 added in the magnetic path as shown in Fig. 3. Generally, a core 1 is formed, and a coil 3 is formed of a conductive wire having an insulating film around the iron core.

[0003] All of the conventional choke coils having the above configuration have the following advantages: (1) The manufacturing process is relatively easy. ■The core shape is simple. ■It is easy to adjust to a predetermined DC superposition characteristic by changing the gap interval. It has the following characteristics.

On the other hand, the problem with the choke coil of the conventional shape is that (1) leakage magnetic flux around the gap is large and spreads over a wide range, generating noise. ■When an alternating current is passed through this choke, noise corresponding to the alternating frequency is generated.

In particular, the leakage magnetic flux is strong in the vicinity of the gap provided in the magnetic path, and this leakage magnetic flux has an adverse effect, such as increasing loss in the iron core and coil conductor, and causing malfunctions in peripheral circuits. Also, when the frequency of the alternating current flowing through this choke coil is an audible frequency, large noise is generated due to mechanical vibration caused by the electromagnetic attraction force generated between the gaps.In order to reduce this noise, the surrounding area is covered with resin. Measures have been taken such as thick coating.

When an amorphous ribbon is used as the iron core material, the loss is superior to that of a silicon steel plate, but when performing gap processing on the core, processing is extremely difficult due to the brittleness of the amorphous material, and the material quality due to processing is extremely difficult. deterioration is likely to occur,
Moreover, processing costs were high. In addition, a large amount of strain is introduced into the processed portion, which causes a significant deterioration of magnetic properties, which has become a problem.

[0007] To deal with this problem, by annealing the wound amorphous core at a temperature higher than the crystallization temperature,
There is a method in which a crystallized layer is formed on the surface of an amorphous ribbon, and this crystallized layer on the surface causes compressive stress to lower the magnetic permeability of the core, thereby providing a predetermined DC superimposition characteristic even without a gap.

However, in this method, the annealing temperature must be strictly controlled, and differences in the thickness of the crystallized layer are likely to occur due to differences in the temperature between the outside and inside of the wound core or the atmosphere.
There was a drawback that the core properties after annealing tended to vary widely.

[0009]

[Problems to be Solved by the Invention] The present invention is a choke coil that reduces the amount of leakage magnetic flux caused by gaps, which is the problem with the conventional choke coils mentioned above, and at the same time reduces noise, which has been a problem up until now. The aim is to provide stable quality at low cost.

0010

[Means for Solving the Problems] The present invention is a choke coil characterized in that an amorphous alloy ribbon having a crystallized layer inside the plate thickness is wound to form a wound iron core. By creating a choke coil having such a configuration, the problems of the conventional choke coil using an amorphous alloy described above were solved, and the present invention was completed.

The iron core material used in the present invention has a composition of TMa.
An amorphous material with a crystallized layer inside the thickness of the plate manufactured by spouting a molten alloy represented by SibBcCdMe onto a moving cooling substrate through a multi-slit nozzle with multiple openings and rapidly solidifying it. It is a quality alloy ribbon.

Here, TM is at least one of Fe, Co, and Ni, M is at least one of Al, Ti, and Zr, and a
, b, c, d, e are each atomic %, a: 70 to 85
, b: 4-18, c: 7-18, d: 0-4, e: 0.
01 to 0.3 and a+b+c+d+e=100. This iron core material can be used as a choke coil if it has the above composition range, but the higher the saturation magnetic flux density, the better the direct current superposition characteristics, so the atomic percent of TM
: It is desirable that a is higher.

[0013] Compared to conventional core materials, this core material is characterized in that the saturation magnetic flux density is almost the same, but the magnetic permeability remains constant up to a large magnetic field, that is, a large excitation current. This feature is obtained by the compressive stress generated by the crystallized layer formed within the thickness of the plate.

In the conventional core, since the magnetic permeability of the core material is high, it is saturated with a small excitation current, and the DC superposition characteristic differs from a predetermined value. When adjusting this direct current superimposition characteristic, a non-magnetic material is inserted into the magnetic path to form a gap 5 as shown in FIG. 3, thereby lowering the apparent magnetic permeability.

On the other hand, by using the above-mentioned amorphous alloy ribbon with low magnetic permeability and a crystallized layer inside the plate thickness as the iron core, the superposition characteristics can be adjusted without forming a gap in the magnetic path. can do. Regarding the thickness of the crystallized layer at this time, the thicker the crystallized layer that causes compressive stress, the smaller the slope of the magnetization curve, and the harder it is to saturate even at high magnetic fields. However, the thickness of the crystallized layer is determined from the viewpoint of mechanical strength.
It is desirable that the thickness per layer be 20% or less of the board thickness.

The specific configuration of the choke coil is as follows:
As shown in Fig. 1, a conductive wire with an insulating film is wound around a core used for the iron core 1, which is made by winding an amorphous alloy ribbon having a crystallized layer inside the thickness of the plate. 3 was formed.

Alternatively, as shown in FIG. 2, in order to simplify the process, the core may be divided and inserted into a coil 3 wound with a conductive wire having an insulating film, and the cut surfaces may be butted together without forming a gap. I don't mind.

Moreover, in order to remove the strain applied to the core when the ribbon is wound, the iron core is annealed at a temperature below the crystallization temperature after the winding process, thereby providing a core with more stable characteristics. can do.

The magnetic permeability of the core material of the present invention can be determined by adjusting the amount of the added elements of Si, B, and M, which are crystallization promoters, and by adjusting the thickness of the crystallized layer by adjusting the nozzle spacing during manufacturing. Since the relative magnetic permeability can be controlled from 50 to 2000, it is possible to supply a core that matches the desired L value and DC superimposition characteristics.

As a result, a choke coil having a desired L value can be manufactured without forming a gap. Since no gap is formed in the magnetic path, leakage magnetic flux and noise generated around the gap shown in the problem are reduced. Moreover, since the crystallization within the thickness of the plate is carried out at the same time as the production of the ribbon, it is possible to produce a large quantity of ribbon with stable performance.

[0021]

[Example] (Example 1) Composition is Fe80.55 Si6
．． 5 An alloy containing B12C0.9 Al0.05 (atomic %) was melted, and the molten metal was passed through a quartz multi-slit nozzle with two slit-like openings (slit width 0.4 mm, slit interval 2 mm). , a plate with a thickness of 40 μm and a width of 25 m made by spraying on the outer peripheral surface of a Cu roll and rapidly cooling it.
m, an amorphous alloy ribbon with a crystallized layer of about 3 μm formed approximately at the center of the plate thickness, wound with an inner diameter of 16 mm and an outer diameter of 24 mm.
A choke coil was produced by annealing this core at about 380° C., and then winding 40 turns of a conductive wire with a diameter of 0.8 mm around the core.

The inductance of this choke coil is 9
As shown in FIG. 4, the inductance was reduced by about 20% (t) when the superimposed current was 4 A.

A conventional choke coil exhibiting the same superimposition characteristics has the same core dimensions and the number of turns of the conductor as described above, and uses an iron-based amorphous ribbon with a relative magnetic permeability of approximately 3000, with approximately This was achieved by forming a gap of 700 μm.

When the above two types of cores were excited with a magnetic flux amplitude of 1 kHz and 1 T, the choke coil using the amorphous alloy ribbon having a crystallized layer inside the plate thickness as the magnetic core of the present invention had about 20 dB more noise. obtained small results. Furthermore, leakage magnetic flux was reduced to about 1/3 or less compared to conventional cores.

(Example 2) The composition was Fe80.5Si6.
5 B12C0.9 Al0.1 (atomic %) alloy was melted, and the molten metal was passed through the quartz multi-slit nozzle having the same two slit-shaped openings as in Example 1.
An amorphous alloy ribbon with a thickness of 44 μm, a width of 25 mm, and a crystallized layer of about 2 μm formed approximately at the center of the thickness is wound on the outer peripheral surface of a Cu roll and produced by rapid cooling, and the inner diameter is 21 mm.
A core with an outer diameter of 29 mm was prepared, and a core of 0.8 mm was prepared around it.
A choke coil was prepared by winding a conductive wire with a diameter of mm 60 turns.

The inductance of this choke coil is 3
．． 5mH, and the superposition characteristic is as shown in Figure 5, when the superposition current is 1.2A, the inductance decreases by about 20% (t).
It was something to do.

A conventional choke coil exhibiting the same superimposition characteristics has the same core dimensions and the number of turns of the conductor as described above, and uses an iron-based amorphous ribbon with a relative magnetic permeability of about 3000, and has a magnetic path of about 360 μm in the core magnetic path. was created by forming a gap between

When the above two types of cores were excited with a magnetic flux amplitude of 1 kHz and 1 T, the choke coil using the amorphous alloy thin strip having a crystallized layer inside the thickness of the plate of the present invention as the magnetic core had a magnetic flux amplitude of about 18 dB. The measurement results were obtained with low noise. Furthermore, leakage magnetic flux was reduced to about 1/3 or less compared to conventional cores.

[0029]

[Effects of the Invention] The present invention eliminates the gap that causes leakage magnetic flux in the magnetic path by using an amorphous alloy ribbon having a crystallized layer inside the plate thickness with low magnetic permeability as the iron core material. , it is no longer necessary to form a gap, and the amount of leakage magnetic flux, which has been a problem in the past, can be significantly reduced, and it is also possible to reduce the noise generated by the attraction force between the gaps. I let it happen.

The above choke coil can adjust the AL value, which was conventionally done by adjusting the cap, by controlling the added elements of the core material, and the variation in the core material is very small. It is industrially valuable since it does not detract from the features of other conventional choke coils.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a choke coil of the present invention.

FIG. 2 is a sectional view of the choke coil of the present invention.

FIG. 3 is a sectional view showing a conventional choke coil.

FIG. 4 is a graph showing the DC superimposition characteristics of the choke coil of Example 1.

FIG. 5 is a graph showing the DC superimposition characteristics of the choke coil of Example 2.

[Explanation of symbols]

1, 1', 1'' Choke coil iron core 2, 2', 2
″ Bobbin 3, 3′, 3″ Coil

Claims (1)

[Claims] 1. A choke coil characterized in that a wound iron core is formed by winding an amorphous alloy ribbon having a crystallized layer inside the plate thickness.