JPS6032310A - Choke coil - Google Patents

Abstract

PURPOSE:To increase effective permeability, to reduce the number of turns of winding, and to reduce DC resistance and Q value of coil by a method wherein the outer circumference of the choke coil is covered by a tape consisting of magnetic material. CONSTITUTION:Flanges 2 and 2' are protruded outward from outer circumference at both ends of a magnetic core 1, and a drum-shaped core 3 of ferrite material is formed. A common-wound winding 4 of magnet wire is wound around the magnetic core 1 of the core 3, a thin tape 5 consisting of magnetic material such as iron, permalloy, and amorphous magnetic material is wound around the outer circumference of the core 3, a heat-shrinkable tube 6 is covered on the outer circumference of the tape, and a choke coil is formed. Also, an insulative terminal stand 8 where four terminals will be buried is adhered to the outside wall of the flange 2, the ends of windings are wound to the terminal 7 and soldered, and a common mode choke is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a choke coil in which a wire is wound around a drum-shaped core, and the outer periphery of the core is covered with a thin tape-like magnetic material.

In telephones or terminal equipment connected to telephone line drop-in lines located near strong electric fields such as medium-wave broadcasting towers, medium-wave electromagnetic waves are coupled, and common mode noise such as interference voltage is generated between the signal line and the ground. This can cause 9 devices to malfunction and 1 to cause communication problems.

Conventionally, common mode choke coils are inserted into telephone lines to attenuate these interfering voltages. However, this type of choke coil uses a drum-shaped core.

Since it is a magnetically open magnetic path, the effective magnetic permeability is low.

In order to obtain a large inductance with an arbitrary shape, the number of turns of the winding is increased, so the DC resistance due to the winding length increases, and due to the stray capacitance between the windings, a frequency resonance with a high Q value may occur at a certain frequency. There are drawbacks that arise. Also, the high Q value of the coil oscillates impulsive noise in response to impulsive voltage such as lightning surge voltage.

It has the disadvantage that it does not easily attenuate noise, so it is desirable that the Q value of the choke coil be small.

The present invention eliminates this drawback of the conventional method and covers the outer periphery of the choke coil with a tape made of magnetic material.

Make the magnetic circuit a closed magnetic path and increase the effective magnetic permeability.

The number of turns of the winding is small, which reduces DC resistance and reduces the Q value of the coil.

In the embodiment of the present invention, as shown in FIG. 1, flanges 2 and 2' are protruded outward from the outer periphery of both ends of a magnetic core 1, and a drum-shaped core 3 of ferrite material is formed. A common winding 4 of magnet wire is wound around the magnetic core 1 of the core 3, and a thin tape 5 made of a magnetic material such as iron, hermalloy, or amorphous magnetic material is further wound around the outer periphery of the core 3. ,
A choke coil is formed by covering the outer periphery of the tape with a heat-shrinkable tube 6. In addition, an insulating terminal block 8 in which four terminals 7 are embedded is glued to the outer wall of one of the collars 2, and the ends of each winding are wrapped and soldered around the terminals 7, and a common mode choke coil is connected. can get.

Therefore, this common mode choke coil
The circuit is as shown in the figure, and input 9 and output 10 are inserted into the telephone line.

-For example, the dimensions of the drum core are outer diameter 14φ shaft diameter 3
．． 4 φ, groove width 3, thread thickness 2 + nm, total length 7 leakage, material ferrite, magnetic core with magnetic permeability 400, polyurethane MMO, 2 types of 16 φ 200 turns, thickness 1
00μ, length 42, and one turn of material (permalloy) is wound. Each line of the magnet wire was electrically connected to a terminal on the terminal block. As a result, the direct current resistance of the winding was 5Ω. On the other hand, in a conventional choke coil in which wires are wound around the same magnetic core, polyurethane copper wire 01 is required to obtain the same inductance.
It was necessary to wind 320 turns of one type of 2φ, and the DC resistance was 12Ω. As is clear from this comparison, the effect of the magnetic tape wound around the outer circumference is significant.

It is important to wrap the magnetic tape 5 so as to tightly contact the ferrite magnetic core and to avoid short-circuiting the ends of the outer magnetic tape. It is still possible to adjust the effective magnetic permeability by adjusting the length of the outer magnetic tape, which is one of the advantages of using magnetic tape.

Another feature of the magnetic tape is that the impedance characteristic of the choke is such that the Q of the choke can be lowered compared to conventional chokes. For example, FIG. 3 shows an example in which permalloy is used as the magnetic tape. In the figure, A shows a comparison between the conventional choke B and the impedance at resonance of the choke according to the present invention. Since YARMALLOY itself has a large magnetic resistance, Q can be lowered.

Normally, a choke coil with a high Q value would be good, but this also depends on its use. For example, when the choke coil according to the present invention is used as a common mode choke, no impedance is inserted into the line, but the choke coil acts as a large impedance for signals (generally noise in this case) applied between the ground and the line. do. Choke coils used for this purpose help prevent equipment from malfunctioning or even being destroyed by noise induced between the line and ground. If a choke coil with a high Q is used, there is a risk that intrusion noise will be amplified at the resonance frequency due to the resonance phenomenon of the choke coil itself. This phenomenon can be alleviated by suppressing the impedance resonance of the choke coil. That is, this objective can be achieved by lowering Q. By changing the material of the magnetic tape in this way, the resonance Q can be lowered.

The choke coil of this invention is based on a drum core.
Since one winding is easy and the outer magnetic tape is simply wound around the outer periphery of the core, it is easy to manufacture, and the various effects described above can be expected.

[Brief explanation of the drawing]

FIG. 1 is an external view of a choke coil according to an embodiment of the present invention.
(a) is a front view, (b) is a bottom view, FIG. 2 is an equivalent circuit diagram of a choke coil according to the present invention, and FIG. 3 is a frequency characteristic diagram of a conventional choke coil and a choke coil according to the present invention. Note that 1: magnetic core, 2.2': tsuba, 3: core, 4: winding. 5: Tape, 6: Heat-shrinkable cheap, 7: Terminal. 8: Terminal block, 9: Input, 10: Output.

Claims (1)

[Claims] 1. A wire is wound around a drum-shaped core made of magnetic material with flanges projecting outward from the outer periphery of both ends of the magnetic core. A choke coil characterized by covering the outer periphery of the core with a thin tape-shaped magnetic material.