JP2003133780A - Noise absorbing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a noise absorbing device which, having a high strength, absorbs noise well. SOLUTION: A ferrite tube 10 is a hollow cylinder comprising a hollow section 11 in which an electric wire (not shown in the figure) is inserted. The ferrite tube 10 is formed by extruding a chlorinated polyethylene, as resin material, with which ferrite powder is mixed as magnetic material by 75-90 wt.% while a polyester adipate mixed as plastic agent by 5-20 wt.%. The ferrite tube 10 is improved in tensile strength from 1.27 MPa to 3,5 MPa and also in extension at cutting from 50% to 74%, compared to a conventional ferrite tube. So it is used as a coating material for an electric wire as well.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a noise absorber which is formed in a tubular shape capable of enclosing an electric wire and which absorbs noise transmitted through the electric wire or radiated from the electric wire.

[0002]

2. Description of the Related Art As a countermeasure against electric wire noise, a ferrite sintered body, which is a magnetic material, is externally fitted around the electric wire to absorb noise conducted through the electric wire (conduction noise) by the ferrite sintered body. And a method of covering the circumference of the electric wire with a conductive foil to prevent noise (radiation noise) radiated from the electric wire from leaking outside.

[0003]

However, since the ferrite sintered body cannot cover a long portion of the electric wire, radiation noise may occur from the portion of the electric wire which is not covered with the ferrite sintered body. . Further, the conductive foil can reflect toward the inside of the foil, but cannot absorb radiation noise and conduction noise. Therefore, these noises may leak to the outside as radiation noise somewhere.

It is possible to mix ferrite with a resin material to form a tube and coat a long portion of an electric wire. However, when the resin material is filled with ferrite, the mechanical properties of the resin material become fragile and cracked. May occur, or lose its elasticity and once crushed, it may not return to its original shape. As described above, the tube having the reduced strength is not suitable for covering the electric wire.

Therefore, the present invention has been made for the purpose of providing a noise absorber having good strength and capable of absorbing noise well.

[0006]

In order to achieve the above-mentioned object, the invention according to claim 1 is formed into a tubular shape capable of enclosing an electric wire, and the electric wire is conducted or the electric wire is removed from the electric wire. A noise absorber that absorbs radiated noise, which is molded into a tubular shape from a resin material mixed with a magnetic material, has a tensile strength of 3 MPa or more, and has an elongation at cutting of 70% or more. Is characterized by.

As described above, the noise absorber of the present invention is formed into a cylindrical shape by the resin material mixed with the magnetic material. Therefore, when the electric wire is inserted, the noise conducted through the electric wire or radiated from the electric wire can be favorably absorbed. Further, the noise absorber of the present invention is 3MP.
It has a tensile strength of a or more and an elongation at break of 70% or more. As described above, since the noise absorber of the present invention has good strength, it can be sufficiently used as a covering material for electric wires. That is, it is possible to follow the bending of the electric wire satisfactorily, and it is possible to maintain the tube shape without cracking even when crushed. Therefore, in the noise absorber of the present invention, it is possible to satisfactorily suppress the generation of the conduction noise and the radiation noise by covering the long portion of the electric wire.

According to a second aspect of the present invention, in addition to the structure of the first aspect, the resin material mixed with the magnetic material is extruded to be molded into the tubular shape. The noise absorber of the present invention is extremely easy to manufacture because it is molded into the tubular shape by extruding the resin material mixed with the magnetic material. Further, in extrusion molding, it is easy to form a linear or spiral slit in the cylinder, and it is also easy to provide a groove for slip prevention on the inner wall surface of the hollow portion. When these processes are performed, the electric wire can be easily inserted and the electric wire can be held well, and the convenience of the noise absorber is further improved. Therefore, in the present invention, in addition to the effect of the invention described in claim 1, there is an effect that the manufacturing can be facilitated and the manufacturing cost can be further reduced, and the convenience can be further improved.

The invention according to claim 3 is the invention according to claim 1 or 2.
In addition to the described structure, the magnetic material is ferrite powder, and is mixed in the resin material in an amount of 75 to 90 wt%. In the present invention, the magnetic material is 75 to 9
0 wt% ferrite powder is used. Therefore, the noise absorber of the present invention can absorb the noise extremely well. Therefore, in the present invention, claim 1 or 2
In addition to the effects of the invention described above, an effect that noise can be absorbed better can be obtained.

The invention according to claim 4 is characterized in that, in addition to the constitution according to any one of claims 1 to 3, the resin material is chlorinated polyethylene. When the resin material is made of chlorinated polyethylene, it is easier to set the tensile strength to 3 MPa or more and the elongation at break to 70% or more as described above. Therefore, in the present invention, in addition to the effects of the invention according to any one of claims 1 to 3, the above-mentioned strength can be more satisfactorily ensured, and the effect that the wire can be used more effectively as a covering material Occurs.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing a configuration of a ferrite tube 10 as a noise absorber to which the present invention is applied. As shown in FIG. 1, the ferrite tube 10
Has a hollow portion 11 into which an electric wire (not shown) can be inserted, and has a hollow cylindrical shape.

The ferrite tube 10 is formed by mixing 75 to 90 wt% of ferrite powder as a magnetic material and 5 to 20 wt% of adipic acid polyester as a plasticizer with chlorinated polyethylene as a resin material and extruding. Obtained by As a plasticizer,
DOS (di-2-ethylhexyl sebacate) may be used instead of the adipic acid polyester.

The ferrite tube 10 thus constructed has the following improved mechanical characteristics as compared with a conventional ferrite tube obtained by mixing the same amount of ferrite powder with chlorinated polyethylene and molding the mixture by a usual method. It was observed. That is, the conventional ferrite tube has a tensile strength of 1.
What was around 27 MPa is ferrite tube 10
Has improved to 3.5 MPa, and the elongation at the time of cutting was 5
What was around 0% improved to 74%.

Since the ferrite tube 10 of the present embodiment has such excellent mechanical characteristics and exhibits good strength, it can be sufficiently used as a covering material for electric wires. That is, it is possible to follow the bending of the electric wire satisfactorily, and it is possible to maintain the tube shape without cracking even when crushed. Further, since the ferrite tube 10 contains 75 to 90 wt% of ferrite powder, it is possible to satisfactorily absorb the noise conducted through the electric wire inserted in the hollow portion 11 or radiated from the electric wire. Therefore, in the ferrite tube 10, it is possible to cover the long portion of the electric wire and suppress the generation of the noise (conduction noise and radiation noise). Furthermore, since the ferrite tube 10 is formed into a cylindrical shape by extrusion molding, it is extremely easy to manufacture and the manufacturing cost can be favorably reduced.

The noise absorption characteristics of the ferrite tube 10 were actually measured. FIG. 2 is a graph showing the magnetic permeability characteristics of the material forming the ferrite tube 10. As shown in FIG. 2, the material forming the ferrite tube 10 has a high magnetic permeability (Permeability) over a wide range of frequencies. And in the ferrite tube 10 made of this material,
As shown in Fig. 3, excellent radiation noise countermeasure effect (effectiv)
eness) was confirmed. Note that the radiation noise countermeasure effect in FIG. 3 represents the difference in electric field strength before and after the noise is radiated from an electric wire using a transmitter and the electric wire is covered with the ferrite tube 10. in this way,
The ferrite tube 10 of the present embodiment is extremely effective as a noise countermeasure for electric wires.

The present invention is not limited to the above-described embodiments, and can be implemented in various forms without departing from the scope of the present invention. For example, various ferrites such as Ni-Zn ferrites and Mn-Zn ferrites can be used as ferrites. In addition to ferrites, various magnetic materials such as soft magnetic material powder containing a metal-based magnetic alloy such as permalloy should be used. You can Also,
Resin materials include NBR, IR, CR, BR, EPD
M, CSM, CPE, AR, FR, VMQ, ECO, E
It is also possible to use rubbers such as U and elastomers such as styrene, urethane, silicone, ester, olefin and nylon.

Further, a linear slit 22 may be formed like the ferrite tube 20 shown in FIG.
A spiral (spiral) slit 32 may be provided like the ferrite tube 30 shown in (B). In these cases, the electric wire can be inserted more easily and the convenience is further improved.

Further, like a ferrite tube 40 shown in FIG. 4 (C), a spiral slit 42 is inserted like the ferrite tube 30, and a groove 43 for slip prevention is formed on the inner wall surface of the hollow portion 41. May be. In this case, by providing the groove 43, the electric wire can be held more favorably, and convenience is further improved.

In FIG. 4A and FIG. 4B, 21,
Reference numeral 31 is a hollow portion similar to the hollow portion 11 of the ferrite tube 10. Further, when the molding is performed by using the extrusion molding as described above, such slits 22, 32,
42 and the groove 43 can be formed extremely easily, and the manufacturing cost can be further reduced.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration of a ferrite tube to which the present invention is applied.

FIG. 2 is a graph showing magnetic permeability characteristics of the ferrite tube.

FIG. 3 is a graph showing a radiation noise countermeasure effect of the ferrite tube.

FIG. 4 is a perspective view showing a configuration of a modified example of the ferrite tube.

[Explanation of symbols]

10, 20, 30, 40 ... Ferrite tube 11, 21, 31, 41 ... Hollow part 22, 32, 42 ... Slit 43 ... groove

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Claims (4)

[Claims] 1. A noise absorber which is formed in a tubular shape capable of enclosing an electric wire, and which absorbs noise conducted through the electric wire or radiated from the electric wire, wherein the resin material is mixed with a magnetic material. A noise absorber, which is formed into a tubular shape, has a tensile strength of 3 MPa or more, and has an elongation at break of 70% or more. 2. The noise absorber according to claim 1, wherein the resin material mixed with the magnetic material is molded into the cylindrical shape by extrusion molding. 3. The noise absorber according to claim 1, wherein the magnetic material is ferrite powder and is mixed in the resin material in an amount of 75 to 90 wt%. 4. The noise absorber according to claim 1, wherein the resin material is chlorinated polyethylene.