TWI868568B - Flat cable - Google Patents

Abstract

[Topic] To provide a flat cable with high current flow efficiency, insulation and safety. [Solution] The flat cable 1 has a pair of strip-shaped conductive thin plates 2 arranged side by side, an insulating layer 3 covering the conductive thin plates 2, and an outer skin protective layer 4 covering the conductive thin plates 2 covered by the insulating layer 3. The conductive thin plates 2 have a plate thickness of less than 0.6 mm and a cross-sectional width of more than 4 mm, the insulating layer 3 has a thickness of more than 0.25 mm, the outer skin protective layer has a thickness of more than 0.25 mm, the overall thickness is less than 3 mm, and the overall width of the cross section is more than 20 mm.

Description

Cable

The present invention relates to a wiring arrangement in which an insulating layer is coated on a conductive thin plate.

Compared with general cables with a slightly circular cross-section, flat cables can be used for various wiring of movable parts such as the roof and doors of a car by taking advantage of their flexibility due to their thinness. In addition, since flat cables can also be wound, they can be used in the internal wiring of electronic equipment such as scanner heads and printing heads (for example, see patent document 1).

Although flat cables have been applied in many fields as mentioned above, most of them are used as dedicated wiring in the above manner. On the power cords and extension cords of electrical appliances used in general households, the vast majority still use cables with a slightly circular cross-section.

However, due to the thickness of general cables, there are cases where they cannot be used for wiring in small places. In addition, for example, general cables are sometimes padded and hidden under carpets and other paving materials, and there are also cases where the cables are located, resulting in a height difference, a poor visual experience, and people may trip due to the height difference. In response to this, flat cables can be installed in the gaps of doors, window frames, etc., and can also be installed in places where general cables cannot be installed, which also helps to increase the freedom of interior design. In addition, if it is a flat cable, there will be no height difference, and there will be no problem of poor visual experience caused by wiring. Therefore, it is considered very necessary to replace the general cables with a slightly circular cross-section with flat cables. [Previous technical literature]

[Patent Document 1] Japanese Patent No. 5309766

[Problem to be solved]

However, in order to replace the general cables with a slightly round cross-section, the flat cable must have the same level of current flow efficiency and insulation as the 100-volt special power cord widely used in households, and there are requirements for safety that can meet certification standards such as UL specifications.

This invention is an invention to solve the above-mentioned problem, and its purpose is to provide a flat cable with high current flow performance, insulation and safety at the same level as traditional power cords. [Means for solving the problem]

In order to solve the above-mentioned problems, the present invention comprises a plurality of strip-shaped conductive thin plates arranged side by side, an insulating layer covering the conductive thin plates, and an outer skin protective layer covering the conductive thin plates covered by the insulating layer. The present invention is characterized in that the thickness of the conductive thin plates is less than 0.6 mm, the cross-sectional width is greater than 4 mm, the thickness of the insulating layer is greater than 0.25 mm, the thickness of the outer skin protective layer is greater than 0.25 mm, the overall thickness is less than 3 mm, and the overall width of the cross section is greater than 20 mm.

In the above-mentioned wiring harness, the above-mentioned insulating layer comprises a first insulating layer for individually coating a plurality of the above-mentioned conductive thin plates, and a second insulating layer for coating the above-mentioned conductive thin plates coated by the above-mentioned first insulating layer. The above-mentioned second insulating layer is preferably coated by extrusion molding a plurality of the above-mentioned conductive thin plates in a side-by-side arrangement.

In the above-mentioned wiring harness, the first insulating layer is preferably a resin coating having a film thickness of 0.1 mm or less.

In the above-mentioned flat cable, the above-mentioned conductive thin plate is preferably made of oxygen-free copper.

In the above-mentioned flat cable, it is preferred to have a carbon film covering the outer protective layer. [Effect of the invention]

According to the present invention, by setting the plate thickness, cross-sectional width, etc. of the conductive thin plate as described above, a high current flow performance equivalent to that of a conventional power cord can be obtained. Furthermore, by setting the thickness of the insulating layer and the thickness of the outer protective layer as described above, high insulation and safety can be achieved.

The wiring harness of one embodiment of the present invention is described with reference to the drawings. As shown in FIG1 , the wiring harness 1 has a pair of strip-shaped conductive sheets 2 arranged side by side, an insulating layer 3 covering the conductive sheets 2, and an outer skin protective layer 4 covering the pair of conductive sheets 2 covered by the insulating layer 3. Furthermore, the insulating layer 3 has a first insulating layer 31 that coats the pair of conductive sheets 2 individually, and a second insulating layer 32 that covers the pair of conductive sheets 2 covered by the first insulating layer 31. Furthermore, the shape shown in FIG1 is an example of the constituent elements of the wiring harness 1, and does not represent the actual size, the proportion of each constituent element, etc.

The thickness of the conductive sheet 2 is less than 0.6 mm, and the cross-sectional width is more than 4 mm, and the thickness is more preferably less than 0.4 mm, and the cross-sectional width is more than 6 mm. As shown in the figure, the thickness of the conductive sheet 2 is 0.25 mm, and the cross-sectional width is 8 mm. In this way, by making the thickness of the conductive sheet 2 thinner, the flat cable 1 itself can be made thinner, and by making the cross-sectional width of the conductive sheet 2 larger, high current flow can be ensured.

However, if the thickness of the conductive sheet 2 becomes less than 0.1 mm, the conductive sheet 2 will be easily damaged by external pressure, etc. In addition, if the cross-sectional width of the conductive sheet 2 increases, the overall width of the flat cable 1 itself will also increase. On the other hand, if the thickness becomes more than 0.6 mm, the width of the flat cable 1 itself will also increase, not only damaging the original advantage of the thinness of the flat cable, but also causing a problem of reduced flexibility. Therefore, the thickness of the conductive sheet 2 is preferably 0.1~0.6 mm, and relative to the thickness, the cross-sectional width of the conductive sheet 2 is preferably 4~10 mm.

The conductive sheet 2 may be made of materials such as copper, pure silver, gold, aluminum, and carbon nanotubes. Carbon nanotubes have extremely high current flowability, are lightweight, and have strong toughness, flexibility, and excellent resilience. Therefore, wiring using carbon nanotubes in the conductive sheet 2 is expected to be developed in a variety of fields. However, like pure silver and gold, due to the high unit price of the product, copper, which has high conductivity and is cheap, is suitable for the conductive sheet 2.

Oxygen-free copper is used in the conductive sheet 2 of this embodiment. Oxygen-free copper is high-purity copper with a purity of 99.96% or more that generally does not contain oxides, and is manufactured in accordance with the product regulations of Japanese industrial standards. Compared with fine copper (tough pitch copper) with a purity of about 99.90% that is widely used as cable conductors, oxygen-free copper has an industrial advantage in that it has lower resistance and distortion. Therefore, the flat cable 1 using oxygen-free copper in the conductive sheet 2 can be used not only for power lines, but also for signal lines that avoid components such as resistance and distortion. In particular, it can be suitably used for speaker cables.

The thickness of the insulating layer 3 is preferably 0.25 mm or more. In the insulating layer 3 shown in the figure, the thickness of the first insulating layer 31 is 0.05 mm, the thickness of the second insulating layer 32 is 0.38 mm, and the thickness of the insulating layer is 0.43 mm. When the thickness of the insulating layer 3 is 0.25 mm or more, the necessary insulation can be achieved, and the safety that meets UL standards (for example, an electrical insulation system that can withstand the test evaluation specified in UL1446) can be obtained. UL standards are product safety standards set by the U.S. certification agency "Underwriters Laboratories Inc. (UL)". For example, products that meet the UL1446 certification standard use a combination of electrical insulation materials with high heat resistance, which ensures that they have electrical insulation functions even when they are exposed to heat and affect each other.

The first insulating layer 31 is preferably a resin coating with a film thickness of less than 0.1 mm. The film thickness of the first insulating layer 31 shown in the figure is 0.05 mm. In the first insulating layer 31 shown in the figure, a nylon coating is used. In addition to mechanical, thermal, and chemical properties, nylon also has excellent electrical properties, so it is often used as a general insulating material for connectors, coil bobbins, etc. Even if the film thickness is 0.05 mm, the necessary insulation can be achieved. In addition, the heat-resistant temperature of the nylon coating is above 200 degrees C, so a cable 1 with excellent heat resistance can be achieved. And the first insulating layer 31 can also use fluororesins with the same or higher heat resistance as nylon.

In addition, in this embodiment, each of the pair of conductive thin plates 2 arranged side by side is covered by the first insulating layer 31, so even if the pair of conductive thin plates 2 are arranged in close contact, it is easy to ensure mutual insulation. In this embodiment, the interval between the pair of conductive thin plates 2 is set to 3.5 mm, and even such an interval can obtain sufficient insulation, and a flat cable 1 that is difficult to cause a short circuit can be achieved. In addition, the interval between the pair of conductive thin plates 2 can also be made narrower, for example, it can also be less than 3 mm. In this way, the overall width of the flat cable 1 can be reduced.

The second insulating layer 32 is made of a resin material having excellent processability, bending resistance, adhesion, and heat resistance. Examples of such resin materials include polymer materials such as polyvinyl chloride, polyethylene, polypropylene, polystyrene, and polyethylene terephthalate. In particular, the material used in the second insulating layer 32 is expected to have heat resistance equal to or higher than that of the nylon coating of the first insulating layer 31. By using such a material, a product that meets the certification standards of the above-mentioned UL specifications can be obtained. Polyvinyl chloride is used in the second insulating layer 32 as shown in the figure, but it is not limited to this. For example, a mixed resin in which polyurethane is mixed with polyvinyl chloride can also be used.

In addition, as described later, the second insulating layer 32 is formed by extrusion to cover the pair of conductive thin plates 2 arranged side by side (already covered by the first insulating layer 31). In other words, the second insulating layer 32 serves as a spacing member for maintaining the spacing between the pair of conductive thin plates 2 and also as an insulating member for preventing short circuits.

The thickness of the outer skin protective layer 4 is preferably above 0.25 mm, and the outer skin protective layer 4 shown in the figure is 0.38 mm. Although the outer skin protective layer 4 can use the same material as the second insulating layer 32, it is better to use a material with excellent shock-absorbing protection, such as thermoplastic elastomer (TPE), which has elasticity like gum at room temperature, is light and strong, and is suitable for use as the outer skin protective layer 4.

The flat cable 1 made of the above materials preferably has an overall thickness of less than 3mm and an overall width of the cross section of more than 20mm. The flat cable 1 shown in the figure has a thickness of 1.87mm and an overall width of 21.22mm. Through this thickness and overall width, a flat cable with development potential in a variety of multi-purpose fields can be obtained. In addition, by setting the plate thickness and cross-sectional width of the conductive sheet 2 as described above, a high current flow performance at the same level as the known power cord can be obtained. In addition, by setting the thickness of the insulating layer 3 and the thickness of the outer protective layer 4 as described above, high insulation and safety can be achieved. In addition, the outer protective layer 4 also contributes to improving heat resistance, so the flat cable 1 is also suitable for automotive wiring equipment such as electric vehicles and hybrid vehicles.

Next, the manufacturing method of the flat cable 1 of the present embodiment will be described with reference to FIGS. 2 to 4 . As shown in FIG. 2 , rolls 10A and 10B of the conductive sheet 2 coated with the first insulating layer 31 (nylon coating) are prepared, and the front ends of the conductive sheets 2 arranged side by side are inserted into the first extrusion molding machine 11. The first extrusion molding machine 11 includes a material supply section for obtaining a resin material and placing it into the device, a compression section for dissolving the resin, and a quantification section for liquefying the resin material and sending it to the mold 12. The resin material (vinyl chloride) constituting the second insulating layer 32 is supplied to the material supply section of the first extrusion molding machine 11. The resin material is dissolved into a liquid, extruded into the mold 12, and coated onto the conductive sheet 2.

FIG3 is a photograph of the actual object of the mold 12. The mold 12 has a supply side mold (left in the photo) for supplying the conductive sheet and a delivery side mold (right in the photo) for delivering the coated conductive sheet 2. The resin material dissolved into a liquid state is extruded into the space between the supply side mold and the delivery side mold, and the second insulating layer 32 formed by the resin material is coated on the conductive sheet 2 by conveying the conductive sheet 2 from the supply side mold. The supply side mold has a shape that narrows in the supply direction of the conductive sheet 2, and two supply ports (not shown in the figure) are provided in its front end portion, and the conductive sheets 2 maintained at a certain interval are respectively supplied from these supply ports. The conductive sheet 2 coated with the second insulating layer 32 is transported to a cooling tank 13 filled with cooling water, and after cooling, is transported to a take-up machine 14. The take-up machine 14 applies pressure in the opposite direction to the extrusion molding machine 11, and by applying pressure, pores are prevented from being generated at the front end.

Next, the conductive sheet 2 coated with the second insulating layer 32 is inserted into the second extrusion molding machine 15. The resin material (TPE) constituting the outer skin protective layer 4 is supplied to the material supply section of the second extrusion molding machine 15. The resin material constituting the outer skin protective layer 4 is dissolved into a liquid state, extruded into the mold 16, and coated on the conductive sheet 2 coated with the first insulating layer 31. FIG4 is a real photograph of the mold 16, in which a supply port (not shown in the figure) for the conductive sheet 2 coated with the second insulating layer 32 is provided at the front end portion of the supply side on the left side. The conductive sheet 2 coated with the outer protective layer in the second extruder 15 is transported to a cooling tank 17 filled with cooling water, and then adjusted in size by a take-up machine 18 and recovered in the form of a roll 19.

According to the manufacturing method, a very long flat cable 1 can be easily manufactured. Since the flat cable 1 manufactured by this manufacturing method can be rolled up, it can be used as an extension cable. In addition, since a product with excellent waterproof and dustproof properties can be obtained, it is also suitable for outdoor use and can be applied to wiring equipment of solar panels.

The insulation resistance and conductor resistance of the flat cable 1 manufactured in the above manner were tested. In the insulation resistance test, after the sample was immersed in water for 1 hour, a voltage of 1500 volts was applied between the conductor and the ground, and the resistance value was measured and calculated at 20 degrees C. In addition, the conductor resistance test was also carried out under the same conditions as above, and the resistance value between the conductors of the sample was measured and calculated. The sample shown in Figure 1 has the same structure as shown in Figure 1, except that the thickness of the conductive sheet 2 is 0.25 mm, the width is 8 mm, and there is no first insulating layer 31. In addition, the strip length is 50m.

Generally speaking, the insulation resistance of the flat cable is required to be above 10 MΩ・km, and the insulation resistance of the flat cable 1 in this example is 89.125~117.8 MΩ・km. In addition, the conductive resistance is required to be below 8.92 Ω/km, and the conductive resistance of the flat cable 1 in this example is 8.764~8.768 MΩ・km. Therefore, it is shown that the flat cable 1 in this example meets the standards of insulation resistance and conductive resistance at the same time, and has the performance that a power cable must have.

Here, a variation of the above-mentioned embodiment is described. The flat cable 1 related to this variation further has a carbon film (omitted in the figure) added to the outer side of the outer protective layer 4. The other structures are the same as the above-mentioned embodiment. The thickness of this carbon film is preferably 0.25 mm or more, for example, 0.38 mm as the above-mentioned outer protective film. The carbon film is composed of, for example, a polymer resin layer containing carbon nanotubes, carbon black, etc. By adding such a carbon film, discharge on the surface of the cable can be promoted, and it is less affected by static electricity, thereby improving the signal transmission performance and obtaining a flat cable that is more suitable for speaker cables.

The present invention is not limited to the above-mentioned embodiments, and various modifications are possible. In the above-mentioned embodiments, a pair of conductive thin plates 2 are arranged side by side, but the number of conductive thin plates 2 is not limited to two, and there may be more than three. For example, if it is a signal line, there may be more than four. For example, in the case of four conductive thin plates 2, the four conductive thin plates 2 may be arranged side by side horizontally, or in a 2×2 arrangement. In addition, the first insulating layer 31 may not be provided, and the first insulating layer 31 may not be provided all around the conductive thin plate 2, but only on a part of the surface.

1: Cable 2: Conductive sheet 3: Insulation layer 31: First insulation layer 32: Second insulation layer 4: Outer protective layer

FIG1 is a cross-sectional view of a cable according to an embodiment of the present invention. FIG2 is a diagram illustrating a method for manufacturing the cable. FIG3 is a photograph of a die used in an extrusion molding machine for coating a second insulating layer. FIG4 is a photograph of a die used in an extrusion molding machine for coating an outer protective layer.

1: Cable arrangement

2: Conductive sheet

3: Insulation layer

31: First insulating layer

32: Second insulation layer

4: Outer protective layer

Claims (5)

A cable, comprising: a plurality of strip-shaped conductive sheets arranged side by side; an insulating layer covering the conductive sheets; and an outer skin protective layer covering the conductive sheets covered by the insulating layer, wherein: the conductive sheets have a thickness of 0.1-0.6 mm and a cross-sectional width of more than 4 mm; the insulating layer has a thickness of more than 0.25 mm; the outer skin protective layer has a thickness of more than 0.25 mm; and the overall thickness is less than 3 mm, and the overall width of the cross section is more than 20 mm. The cable as described in claim 1, wherein the insulating layer has a first insulating layer for individually coating the plurality of conductive sheets, and a second insulating layer for coating the conductive sheets coated by the first insulating layer, wherein the second insulating layer is coated by extruding the plurality of conductive sheets arranged side by side. The cable as described in claim 2 is characterized in that the first insulating layer is a resin coating with a film thickness of less than 0.1 mm. A ribbon cable as described in any one of claims 1 to 3, characterized in that the conductive sheet is made of oxygen-free copper. The cable as described in any one of claims 1 to 3 is characterized in that it further includes a carbon film covering the outer periphery of the outer protective layer.