JPH02251107A - Choke coil - Google Patents

Abstract

PURPOSE:To obtain a choke coil characterized by high saturation magnetomotive force, less magnetic flux leakage and high permeability by inserting a spacer which is formed with a magnetic material whose permeability is lower than that of a core material and whose saturation magnetic flux density is higher than that of the core material into a gap. CONSTITUTION:In a choke coil A, a part of a toroidal core 1 which is formed with a high permeability magnetic material such as an amorphous material is cut out, and a gap 2 is provided. A spacer 3 comprising a magnetic material characterized by low permeability and high saturation magnetic flux density is inserted into the gas 2. A conductor wire 4 such as polyurethane coated copper wire and the like is wound around the core 1 many number of turns, and the coil is formed. When a large current is made to flow through the conductor wire 4 until the magnetic flux density in the core 1 is saturated, the choke coil having highly saturated magnetomotive force is obtained. As the gap 2, the magnetic material whose permeability is relatively low is used. In this way, the saturation magnetomotive force of the choke coil having the high permeability can be made high, and the leaking magnetic flux at the gap part is made less. Magnetic interference with surrounding electric parts can be suppressed.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a choke coil.

[Background technology]

A choke coil using a core made of a high magnetic permeability material such as an amorphous core has a problem in that the saturation magnetomotive force (the magnetomotive force when the magnetic flux density inside the core reaches a saturation value) is small. That is, when a current is passed through the conducting wire, the inside of the core easily reaches the saturation magnetic flux density with a relatively small current value.

For this reason, in conventional choke coils, a part of the annular core is cut out to provide a gap to increase the saturation magnetomotive force, and a resin spacer is inserted into the cap to determine the gap length.

[Problem to be solved by the invention]

However, conventional choke coils in which a resin spacer is used in the gap have the drawback that magnetic flux leakage is large in the gap, causing magnetic interference with surrounding electronic components and causing noise. Moreover, in such a choke coil, if the gap length is increased to increase the saturation magnetomotive force, the leakage flux will increase, and if the cap length is decreased to reduce the leakage flux, the saturation magnetomotive force will not be sufficiently high. There were contradictory issues.

The present invention has been made in view of the above-mentioned drawbacks of the conventional example, and its object is to provide a choke coil with high saturation magnetomotive force and high magnetic permeability with little magnetic flux leakage.

[Means to solve the problem]

Therefore, in the choke coil of the present invention, a gap is provided by cutting out a part of the annular core made of a high magnetic permeability material, and a spacer is formed of a magnetic material having lower magnetic permeability and higher saturation magnetic flux density than the core material. is inserted into the cap, and a conductive wire is wound around the core.

[Effect]

In the present invention, in a choke coil using a core with high magnetic permeability, a gap is provided in the core, so that the saturation magnetomotive force of the choke coil can be increased.

Moreover, since a spacer made of magnetic material (magnetic permeability>1) is inserted into the gap of the core, the magnetic flux can be confined within the spacer made of magnetic material even in the gap part, reducing magnetic flux leakage, and the surrounding electrons It is possible to suppress the generation of noise by reducing magnetic interference with components.

Furthermore, if a magnetic material with a high magnetic permeability close to that of the core is used as a spacer material, the magnetic flux density inside the core becomes more likely to saturate as it approximates a core without a cap, but the choke of the present invention Since the coil uses a magnetic material with low magnetic permeability, a large saturation magnetomotive force can be maintained.

Furthermore, since a magnetic material with a high saturation magnetic flux density is used as the spacer, the spacer saturates before the core, and the increase in magnetic flux inside the core is not suppressed and becomes more saturated. You can get a choke coil that is difficult to use.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows an example of the choke coil of the present invention. This choke coil A has a cap 2 formed by cutting out a part of a troital-shaped core made of a magnetic material with high magnetic permeability such as amorphous paulownia wood, and a saturation magnetic flux with low magnetic permeability in this gap 2. A spacer 3 made of a high-density magnetic material is inserted, and a conducting wire 4 such as a polyurethane-coated copper wire is wound around the core 1 many times.

The one shown in Fig. 2 assumes a choke coil A in which a space cap 2 with a gap length (.-2.2 mm) is provided on a square core 1 with a magnetic permeability of 50,000 μm, and a spacer 3 with a magnetic permeability of 10 μm is inserted into the cap 2. This is a magnetic flux density distribution diagram simulated by element analysis using a computer.The inductance in this choke coil was 375 μH.

On the other hand, the one shown in FIG. 3 assumes a conventional choke coil B in which a square core 1a with a magnetic permeability of 50,000 μm is provided with a space cap 2a with a cap length of 1 o = 0.26 mm, and a finite element 2 is a magnetic flux density distribution diagram simulated by method analysis.

As is clear from a comparison of FIGS. 2 and 3, the choke coil A of the present invention and the choke coil B of the conventional example have approximately the same inductance, and the gap length of the choke coil B of the present invention is on the contrary. Although the choke coil A is larger, the leakage magnetic flux is smaller in the choke coil A of the present invention. In addition, both choke coils A,
The saturation magnetomotive force of B was about the same.

In this way, in the choke coil A of the present invention, since the gap 2 is provided in the core 1, a large current can be passed through the conductor 4 before the magnetic flux density inside the core 1 is saturated, and a high saturation phenomenon can be achieved. A choke coil with magnetic force is obtained. Moreover, since the spacer 3 made of a magnetic material is inserted into the cap 2 instead of a space gap, the magnetic flux can be confined within the spacer 3 and leakage magnetic flux can be reduced. Here, if the magnetic permeability of the spacer 3 is 1, it is the same as in the case of a resin spacer, so the spacer 3 is made of a magnetic material (magnetic permeability μ
〉1) However, conversely, if the magnetic permeability is as high as that of the core 1, it will approximate the state without the cap 2 and the saturation magnetomotive force will be small, so it is necessary to use a magnetic material with a relatively low magnetic permeability. Is it necessary to use it?

In addition, if the saturation magnetic flux density of the spacer material is low, the magnetic flux density of spacer 3 will be saturated before the magnetic flux density of core 1 is saturated, so the magnetic material of spacer 3 will have a saturation level equal to or higher than that of core 1. It is necessary to use one with high magnetic flux density. Furthermore, in the choke coil A of the present invention,
The point where the magnetic permeability in the gap becomes larger than that of the spatial gap contributes to lowering the saturation magnetomotive force, while the point where the gap length increases and the leakage flux decreases contributes to increasing the saturation magnetomotive force. Therefore, it is possible to obtain a high saturation magnetomotive force comparable to or higher than that of the choke coil B of the conventional example.

Therefore, as the magnetic material for the spacer 3, it is appropriate to use a material with a magnetic permeability μ of about several 10 and a high saturation magnetic flux density; for example, a powder magnetic core or the like may be used.

〔Effect of the invention〕

According to the present invention, the saturation magnetomotive force of a choke coil with high magnetic permeability can be increased. At the same time, leakage magnetic flux at the gap can be reduced, so magnetic interference with surrounding electronic components can be suppressed, and the choke coil can be prevented from causing noise.

[Brief explanation of drawings]

Fig. 1 is a plan view of an embodiment of the present invention, Fig. 2 is a magnetic flux density distribution diagram obtained by finite element analysis of the same choke coil as described above, and Fig. 3 is a diagram of the conventional choke coil obtained by finite element analysis. It is a magnetic flux density distribution diagram. 1...Core 2...Gap 3...Spacer 4...Conductor Patent Applicant Murata Manufacturing Co., Ltd. Representative Patent Attorney Masaru Nakano Fusato Sa1

Claims (1)

[Claims] (1) A gap is created by cutting out a part of the annular core of a high magnetic permeability material, and a spacer made of a magnetic material with lower magnetic permeability and higher saturation magnetic flux density than the core material is inserted into the gap. , a choke coil characterized by a conductor wound around the core.