JPH0424570Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial field of application] This invention relates to a shield structure for electric wires, and in particular uses stainless steel fiber for the shield. [Conventional technology] Conventional wire shields include braided tin-plated annealed copper wire, horizontally wound tin-plated annealed copper wire, aluminum and polyester, and annealed copper wire and wood. It is known that it is made by braiding cotton thread.

[Problem that the invention attempts to solve]

However, according to the conventional technology, the above and above have excellent shielding properties but poor bending resistance and flexibility, and the above and above have excellent bending resistance and flexibility but poor shielding properties. However, there was a problem in that there was no one that satisfied all of the shielding effect, bending resistance, and flexibility.

This invention was made by focusing on the problems of the conventional technology, and aims to obtain a shielding structure for electric wires that satisfies all of shielding properties, bending resistance, and flexibility. .

[Means for solving problems]

The electric wire shield structure of this invention consists of a shield made by braiding spun yarn made of thin stainless steel fibers and tin-plated copper wire, and placed on the outside of the conductor with an insulator interposed therebetween.

[Effect]

Since tin-plated copper wire is used as a shield, it has a sufficient shielding effect to prevent electrostatic induction and electromagnetic induction, and in conjunction with the tin-plated copper wire,
Since stainless steel fibers made from stainless steel, which is a hard material with low frictional resistance, are used, sufficient flexibility and bending resistance can be obtained.

In particular, if stainless steel fibers are used whose outer surfaces are not smooth like the outer surface of a cylinder, but whose cross sections are rectangular or have many fine wrinkle-like curves formed on the outer periphery of the cross sections, the outer surface of the fibers Diffuse reflection of noise occurs at the point where the noise is attenuated during this diffuse reflection, so that the shielding effect is enhanced. Furthermore, when the stainless steel fibers have a rectangular cross section, the probability that adjacent fibers will come into surface contact with each other increases, thereby increasing the girdle effect in a low frequency region with a long wavelength.

〔Example〕

FIG. 1 shows an embodiment of this invention, in which a shield 3 is connected to the outer periphery of a central conductor 1 via an insulator 2.
A protective coating 4 is applied to the outer periphery of the shield 3 to form an electric wire 5. The insulator 2 and the protective coating 4 are made of polytetrafluoroethylene (PTFE),
Tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), Tetrafluoroethylene-
It is made of a material selected from fluorine resins such as ethylene copolymer (ETFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), polyvinylidene fluoride (PVdF), and others.

As shown in FIG. 2, the shield 3 is made by braiding stainless threads 32 made by spinning stainless steel fibers 31. The stainless steel fiber 31 does not have a smooth outer surface like the outer surface of a cylinder, but has a rectangular cross section or a shape in which many fine wrinkles are formed on the outer periphery of the cross section, and the outer surface has a shape with a fiber direction. An ultra-fine material (trade name: "Naslon" manufactured by Nippon Seisen Co., Ltd.) with ridge lines, wrinkles, etc. formed thereon and a diameter of approximately 5 to 20 μm is used. In this embodiment, the shield 3 is constructed by braiding only the stainless thread 32 made by spinning the stainless steel fibers 31, but the stainless steel thread 32 and tinned annealed copper wire or the like are alternately arranged. The shield 3 can also be formed by braiding.

Since the shield 3 uses the ultrafine stainless steel fibers 31 as described above, it has excellent flexibility and bending resistance. In particular, the stainless steel fiber 31 has a high hardness, so the surface slips easily, and the stainless steel thread 3
Since the frictional resistance between the stainless steel fibers 31 and the stainless steel threads 32 constituting the shield 2 is small, the diameter of the stainless steel fibers 31 and the frictional resistance are both small, and the flexibility of the shield 3 is reduced. It has excellent bending resistance.

In addition, since the stainless steel fiber 31 has a rectangular cross section or a shape with many fine wrinkle-like curves formed on the outer periphery of the cross section, on the surface of one stainless steel fiber 31, Since noise is repeatedly diffusely reflected and attenuated between the surfaces of the stainless steel fibers 31, the shield 3 prevents certain electrostatic induction and electromagnetic induction.

The inventor conducted a series of tests to confirm the bending resistance, flexibility, and shielding effectiveness of the shield 3. The test will be explained below.

The electric wires used for the test were (a) an electric wire braided with only tin-plated annealed copper wire (density 92%) as shield 3;

(b) As a shield 3, an electric wire (density 95%) is made by alternately braiding tin-plated annealed copper wire and stainless steel yarn 32 (apparent wire number 20 ^s ) spun from the same stainless steel fiber 31 as in the above embodiment.

(c) As the shield 3, an electric wire (95% density) is made by braiding only stainless steel yarn 32 spun from the same stainless steel fiber 31 as in the above embodiment.

These electric wires a, b, and c all use tin-plated annealed copper wire as the conductor 1 and as the insulator 2.
Using FEP and silicon HST as protective coating 4
The electric wires a, b, and c were kept under the same conditions, and only the shield 3 was of the three types described above.

(Flexing Resistance) As shown in Fig. 3, the bending resistance test was performed by passing an electric wire through a mandrel 6, connecting a disconnection detector 7 to the lower side thereof, and applying a load (w) of 1 kg. With the conductor and shield connected at the upper end, the upper side was bent at a rate of 30 times per minute, with one cycle of a → b → c → a, and the number of bends until the shield broke was tested (MIL C-
13777).

As a result, wire a was tested 12,000 times, wire b was tested over 80,000 times, and wire c was tested over 80,000 times. That is, the shield 3 of the electric wire a broke after the number of bends described above, but the wires B and C did not break even after the number of bends exceeded the number of bends.

As a result, the bending resistance of electric wires b and c using a shield made of stainless steel fibers is superior to that using only tin-plated annealed copper wire, and the bending resistance of electric wires b and c using a shield made of stainless steel fibers is superior to that using only tin-plated annealed copper wire. It turns out that there is not much difference.

(Flexibility) As shown in Figure 4, the flexibility test
A 1 m long electric wire was formed into a ring shape (Fig. 4 1), a load w was applied to the lower end of the ring (Fig. 4 2), and the lateral diameter A of the ring was measured at a position 120 mm from the top of the ring. Loads of 500g and 1000g were applied individually. As a result, the fifth dimension is set as the dimension A.
The values shown in the table in the figure were obtained. As a result, it was found that the flexibility of wires b and c using a shield made of stainless steel fibers was superior to that using only tin-plated annealed copper wire, and that the flexibility between wires b and c was It can be seen that there is not much difference.

(Shielding effect) In the shielding effect test, a high frequency voltage was applied by an oscillator 9 using a copper pipe 8 as a noise source as shown in Fig. 6, and an electric wire (only conductor 1 and shield 3 are shown) inserted into the pipe 8 ) was measured with a voltmeter 10, and this was taken as the noise voltage. Here, the shielding effect is defined as the decibel value of the noise voltage V _N with respect to the voltage V _O applied to the pipe 8. This test method complies with the National Space Exploration Agency's instruction manual NASDA-QTS:1012.

The measurement results in this test are shown in the table of FIG. Shielding effect shown in this table [αB]
is obtained by αB=20logV _O /V _N. FIG. 8 is a graph showing this shielding effect. Here, (a), (b), and (c) indicate the electric wires a, b, and c, and d means an electric wire using a shield 3 formed by horizontally winding a tin-plated annealed copper wire, A comparison is shown for reference.

As a result, it can be seen that the shielding effect is as follows: wire a > wire b > wire c; however, wires b and c have a better shielding effect than the horizontally wound shielded wires made of tin-plated annealed copper wire, and wires also made of stainless steel fibers. Among electric wires b and c, electric wire b, which uses both stainless steel fibers and tin-plated copper wire, has better shielding properties than electric wire c, which is made only of stainless steel fibers.

As a result of these tests, it was found that when stainless steel yarn made from spun stainless steel fibers was used as a shielding material, it had better bending resistance and flexibility than when tin-plated annealed copper wire was used as a shielding material.
It was also found that although the shielding effect was slightly inferior, it was superior to the case where tin-plated annealed copper wire was wound horizontally, and it was sufficiently usable.

[Effect of idea]

As explained above, for conventional electric wires,
It used to be that if any one of shielding properties, bending resistance, or flexibility was superior, the other would be inferior, but in this invention, we combined stainless steel fiber's excellent bending resistance and flexibility, and tin plating. Combined with the excellent shielding properties of copper wire, it has the unique effect of being able to obtain all of the shielding properties, bending resistance, and flexibility required for shielding electric wires in just the right amount. .

[Brief explanation of the drawing]

Figure 1 is a perspective view showing an embodiment of this invention;
The figure is a partially cutaway enlarged perspective view of the shield, Figure 3 is an explanatory diagram of the bending test, Figure 4 1 is a front view of the state before the start of the flexibility test, and Figure 2 is the shield during the flexibility test. A front view showing the condition, Figure 5 is a diagram showing the results of the flexibility test, Figure 6 is an explanatory diagram showing the outline of the shielding effect test, Figure 7 is a diagram showing the results of the shielding effect test, Figure 8 It is a graph showing test results of shielding effectiveness. 1...Conductor, 3...Shield, 31...Stainless steel fiber, 32...Stainless steel thread, 5...Electric wire.

Claims (1)

[Claims for Utility Model Registration] (1) A shield made of a braid of spun yarn made of thin stainless steel fibers and tin-plated copper wire is placed on the outside of the conductor with an insulator interposed therebetween. shield structure for electric wires. (2) The electric wire shielding structure according to claim 1, wherein the stainless steel fibers have a diameter of about 5 to 20 μm and have an irregular cross section.