cable

Abstract

To provide a cable capable of reducing a copper use amount, and suppressing disconnection on a shield layer due to external force or self weight.SOLUTION: A cable 1 comprises: a cable core 3 having one or more electric wires 2; a shield layer 4 covering the surrounding of the cable core 3; a sheath 5 covering the surrounding of the shield layer 4. The shield layer 4 is formed of a braiding shield obtained by braiding a plurality of first metal element wires 41 formed of an aluminum or aluminum alloy, and a plurality of second metal element wires 42 formed of a copper or copper alloy, so that the first and second metal element wires cross each other, and an outer diameter of the second metal element wire 42 is larger than that of the first metal element wire 41.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a cable. [Background technology]

[0002] Conventionally, a cable connected to a servo motor or the like includes, for example, a composite cable including a plurality of signal wires made of twisted-pair wires and a plurality of power wires arranged around the signal wires (see, for example, Patent Document 1). In this cable, a shield layer made of a braided shield formed by braiding metal wires made of tin-plated annealed copper wires is provided to collectively cover the plurality of signal wires and the plurality of power wires. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-313144 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, the movement toward decarbonization has accelerated, and the global demand for copper as a decarbonized resource has increased, causing the price of copper to skyrocket. For example, the price of copper is more than four times that of aluminum. Therefore, in electric wires and cables, it is desirable to reduce the amount of copper used in the conductor and shielding layer while taking into account the impact on conductor resistance and shielding characteristics. In particular, in cables, the outer diameter tends to increase as the number of electric wires increases. When the outer diameter of a cable increases, the amount of copper used as the metal wires that make up the shielding layer also increases, which could significantly increase costs.

[0005] Furthermore, when a cable's shielding layer is made of metal wires made of copper or a copper alloy, the weight of the cable tends to increase as the number of metal wires used increases. If the weight of the shielding layer accounts for a large proportion of the cable's overall weight, the shielding layer is subjected to a large load, for example, when the cable is bent, due to external forces acting on the cable or the cable's own weight. This raises the risk that the metal wires that make up the shielding layer may break due to the effects of external forces or the cable's own weight.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a cable that can reduce the amount of copper used and that is less likely to cause breakage in the shield layer due to external forces or its own weight. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, the present invention provides a cable comprising a cable core having one or more electric wires, a shielding layer surrounding the cable core, and a sheath surrounding the shielding layer, wherein the shielding layer is a braided shield in which a plurality of first metal wires made of aluminum or an aluminum alloy and a plurality of second metal wires made of copper or a copper alloy are braided together so that they cross each other, and the outer diameter of the second metal wires is larger than the outer diameter of the first metal wires. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a cable in which the amount of copper used can be reduced and in which breakage of the shield layer due to the influence of external forces or its own weight is unlikely to occur. [Brief explanation of the drawings]

[0009] [Figure 1] 1A is a cross-sectional view showing a cross section perpendicular to the longitudinal direction of an electric wire according to an embodiment of the present invention, FIG. 1B is a schematic diagram of a shielding layer, and FIG. 1C is a schematic diagram of an inner shielding layer. [Figure 2] FIG. 4 is a cross-sectional view showing a cross section perpendicular to the longitudinal direction of an electric wire according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] [Embodiment Mode] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0011] Fig. 1(a) is a cross-sectional view showing a cross section perpendicular to the longitudinal direction of an electric wire according to this embodiment. Fig. 1(b) is a schematic diagram of a shielding layer (hereinafter also referred to as an outer shielding layer), and Fig. 1(c) is a schematic diagram of an inner shielding layer. The cable 1 is used, for example, as a cable for fixed parts connecting an industrial robot to a control device or the like in a factory or the like. Note that the cable 1 may also be used as a cable for fixed parts of factory equipment other than an industrial robot, or may even be used as a cable to be wired inside an automobile or the like.

[0012] As shown in Figure 1(a), the cable 1 includes a cable core 3 having one or more electric wires 2, a shielding layer 4 (hereinafter also referred to as the outer shielding layer 4) surrounding the cable core 3, and a sheath 5 surrounding the shielding layer 4.

[0013] (Electric wire 2) The electric wire 2 includes a plurality of signal lines 21 for signal transmission and a plurality of power lines 22 for power supply. In other words, the cable 1 is a composite cable that combines the signal lines 21 and the power lines 22.

[0014] The signal wire 21 is made of a twisted pair 212 formed by twisting together a pair of insulated wires 211. Each of the insulated wires 211 constituting the twisted pair 212 has a conductor 211a formed by twisting together a plurality of strands (e.g., strands having an outer diameter of 0.1 mm or less) made of tin-plated annealed copper wire or the like, and an insulator 211b provided to cover the periphery of the conductor 211a. The insulator 211b is made of a fluororesin such as ETFE (tetrafluoroethylene-ethylene copolymer), FEP (tetrafluoroethylene-hexafluoropropylene copolymer), or PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer).

[0015] Here, a case is shown in which six (six pairs) of signal wires 21 (twisted wire pairs 212) are used, but the number of signal wires 21 (twisted wire pairs 212) is not limited to this. In other words, the number of signal wires 21 may be one or more than six. It is more desirable that each twisted wire pair 212 be twisted with a different twist pitch to suppress crosstalk (noise) between the twisted wire pairs 212. Furthermore, the signal wires 21 are not limited to twisted wire pairs 212. For example, the signal wires 21 may be coaxial cables.

[0016] The power wire 22 includes a conductor 22a formed by twisting together multiple strands (e.g., strands having an outer diameter of 0.1 mm or less) made of tin-plated annealed copper wire or the like, and an insulator 22b provided to cover the conductor 22a. The insulator 22b is made of a fluororesin such as ETFE (tetrafluoroethylene-ethylene copolymer), FEP (tetrafluoroethylene-hexafluoropropylene copolymer), or PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer). The power wire 22 has a larger conductor cross-sectional area and outer diameter than the insulated wires 211 that make up the twisted pair wire 212. While the present example shows the use of eleven power wires 22, the number of power wires 22 is not limited to this. In other words, the power wire 22 may be one or more than eleven.

[0017] (Cable core 3) The cable core 3 has an inner shield layer 8 that surrounds the electric wires 2 and is located inside the shield layer 4. For example, in the cable 1 shown in FIG. 1(a), the cable core 3 has an inner layer core 3a that includes a plurality of signal wires 21, an inner shield layer 8 that surrounds the inner layer core 3a, and an outer layer core 3b that includes a plurality of power wires 22 twisted around the inner shield layer 8. Note that while the cable 1 shown in FIG. 1(a) has a structure in which the electric wires 2 are disposed around the inner shield layer 8, this is not limiting. In other words, the cable core 3 does not necessarily need to have the electric wires 2 disposed between the inner shield layer 8 and the shield layer 4. This allows the outer diameter of the cable 1 to be reduced, thereby reducing the amount of metal wires made of copper or copper alloy that constitute the shield layer disposed outside the cable core. As a result, the cost of the cable 1 can be reduced.

[0018] The inner layer core 3a is formed by twisting together six (six pairs) of signal wires 21 (twisted pairs 212). Since stress concentrates in the center of the cable when it is bent, in this embodiment, the inner layer core 3a is formed by twisting the signal wires 21 (twisted pairs 212) in a spiral shape around the insulator 6. This makes it possible to prevent the stress from concentrating on the signal wires 21 (twisted pairs 212) when it is bent, thereby preventing the transmission characteristics of the signal wires 21 (twisted pairs 212) from deteriorating.

[0019] For example, a filament such as staple fiber (spunbond) yarn can be used as the filler 6. Staple fiber yarn has appropriate cushioning properties and does not break even when bent, making it particularly suitable for use in applications where the cable 1 is bent. The filament used for the filler 6 is not limited to staple fiber yarn, and materials made of, for example, string, paper, jute, nonwoven fabric, etc. can also be used. Furthermore, the filler 6 is not limited to a filament, and for example, a strip-shaped material can also be used. By providing cushioning properties, the filler 6 distributes stress applied to the signal line 21 (twisted pair wire 212) when bent, thereby also fulfilling the role of suppressing deterioration of the transmission characteristics of the signal line 21 (twisted pair wire 212).

[0020] The twist direction of the twisted pair wire 212 is preferably opposite to the twist direction of the conductor 211a and the inner core 3a. The twist direction of the conductor 211a is the same as the twist direction of the inner core 3a. This is because if the twist direction of the twisted pair wire 212 were the same as the twist direction of the conductor 211a and the inner core 3a, the strands constituting the conductor 211a would be repeatedly twisted in the same direction, which could cause the strands to be squeezed when bent, etc. By twisting the twisted pair wire 212 in the opposite direction to the twist direction of the conductor 211a and the inner core 3a, it is possible to prevent the strands from breaking and improve resistance to bending.

[0021] The twisting direction of the conductor 211a is the direction in which the wires rotate from one end to the other end when viewed from one end of the insulated wire 211. The twisting direction of the twisted pair 212 is the direction in which the insulated wires 211 rotate from the other end to the one end when viewed from one end of the inner core 3a. The twisting direction of the inner core 3a is the direction in which the twisted pair 212 rotates from the other end to the one end when viewed from one end of the inner core 3a.

[0022] A first pressure winding tape 7 is spirally wound around the inner core layer 3a. The first pressure winding tape 7 can be a paper tape or a tape made of nonwoven fabric. The first pressure winding tape 7 is wound so as to have a substantially circular shape in cross section. Each of the signal wires 21 (twisted pair wires 212) that make up the inner core layer 3a is in contact with the inner peripheral surface of the first pressure winding tape 7. An inner shielding layer 8 is provided around the first pressure winding tape 7. Details of the inner shielding layer 8 will be described later.

[0023] A resin tape 9 is spirally wound around the inner shield layer 8. The resin tape 9 serves to improve sliding between the power wire 22 constituting the outer core 3b and the inner shield layer 8, thereby suppressing wear. The resin tape 9 is preferably made of a material that is resistant to wear and has good sliding properties, such as nylon or a fluororesin such as PTFE (polytetrafluoroethylene) or ETFE (tetrafluoroethylene-ethylene copolymer). The resin tape 9 may not be provided depending on the application of the cable 1, the wiring location, etc.

[0024] Eleven power wires 22 are spirally twisted around the resin tape 9 to form the outer layer core 3b. In this embodiment, the outer layer core 3b is formed by twisting the power wires 22 and the inserts 11 together. The inserts 11 shape the outer shape of the cable 1 so that it is circular, and are interposed between the power wires 22 constituting the outer layer core 3b to prevent the power wires 22 from wearing out when bent, etc. In this embodiment, adjacent power wires 22 do not contact each other in the outer layer core 3b. The inserts 11 used in the outer layer core 3b can be made of staple yarn, as with the inserts 6 used in the inner layer core 3a. As described above, the cable core 3 may not have the outer layer core 3b depending on the application of the cable 1, the wiring location, etc. In this case, the cable 1 becomes a cable core 3 in which, for example, a resin tape 9 or a second holding winding tape 10 (described later) is provided around the inner shielding layer 8 as needed, and a shielding layer 4 is provided on the outside of this cable core 3.

[0025] A second pressure winding tape 10 made of paper tape or nonwoven fabric is spirally wound around the outer core 3b. The second pressure winding tape 10 is wound so that it has a substantially circular shape in cross section by appropriately adjusting the amount and arrangement of the fillers 11. All of the power wires 22 that make up the outer core 3b are in contact with the inner surface of the second pressure winding tape 10 and the outer surface of the resin tape 9. The second pressure winding tape 10 may not be provided depending on the application of the cable 1, the wiring location, etc.

[0026] (Sheath 5) An outer shield layer 4 is provided around the second holding winding tape 10, and a sheath 5 made of an insulator is provided to cover the outer shield layer 4. The sheath 5 may be made of a resin composition with a base resin such as polyvinyl chloride (PVC) resin or polyurethane (PU) resin, so as to protect the cable 1 from external forces.

[0027] (Outer shield layer 4) As shown in FIG. 1(b), in the cable 1 according to this embodiment, the outer shielding layer 4 is made of a braided shield formed by braiding a plurality of first metal wires 41 made of aluminum or an aluminum alloy and a plurality of second metal wires 42 made of copper or a copper alloy so that the first metal wires 41 and the second metal wires 42 cross each other.

[0028] This allows a reduction in the amount of copper used, allowing the outer shield layer 4 to be lighter than a braided shield made only of metal wires made of copper or a copper alloy, thereby reducing the weight of the entire cable 1. Furthermore, since the outer shield layer 4 includes second metal wires 42 made of aluminum or an aluminum alloy with low yield strength, the outer shield layer 4 becomes softer, making the cable 1 easier to bend. Furthermore, compared to a braided shield made only of metal wires made of aluminum or an aluminum alloy, the outer shield layer 4 is less likely to cause breakage of the metal wires due to rubbing against each other when the cable 1 is bent. This is because a braided shield in which first metal wires 41 made of aluminum or an aluminum alloy and second metal wires 42 made of copper or a copper alloy are braided together is more likely to cause wear when the metal wires rub against each other than a braided shield in which metal wires made of aluminum or an aluminum alloy are braided together.

[0029] Furthermore, when connecting the terminal of cable 1 to a substrate, etc., it has been difficult to connect by soldering a braided shield composed only of metal wires made of aluminum or an aluminum alloy. In contrast, in this embodiment, outer shield layer 4 contains second metal wires 42 made of copper or a copper alloy, making it easy to connect by soldering.

[0030] Furthermore, when processing the terminal of the cable 1, the outer shield layer 4 may be exposed at the terminal of the cable 1, the exposed outer shield layer 4 (braided shield) may be unraveled using a dedicated tool or the like, and the unraveled, separated metal wires 41, 42 may be bundled so as to branch from the cable core 3 and connected to a substrate or the like. In this case, the bundled metal wires 41, 42 are connected to the substrate or the like by crimping or soldering. In this embodiment, the outer shield layer 4 includes the first metal wires 41 made of low-yield strength aluminum or an aluminum alloy, which makes it easier to unravel the outer shield layer 4 than a braided shield made only of copper. Furthermore, when bundling the unraveled metal wires 41, 42, the first metal wires 41 play a role in maintaining the shape, making it easier to bundle the metal wires 41, 42 into a desired shape. When bundling the metal wires 41 and 42, the first metal wire 41 is placed at the center and the second metal wire 42 is wound spirally around it, which makes it easier to connect them by soldering.

[0031] In this embodiment, the first metal wires 41 made of aluminum can be, for example, aluminum wires made of pure aluminum. The first metal wires 41 made of an aluminum alloy can be, for example, aluminum alloy wires made of an Al-Zr alloy, an Al-Ni-Zr alloy, an Al-Co-Zr alloy, or an Al-Fe-Zr alloy. The second metal wires 42 made of copper can be, for example, tin-plated annealed copper wires in which tin plating is provided on the surface of a annealed copper wire. The second metal wires 42 made of a copper alloy can be, for example, copper alloy wires made of a copper alloy containing a predetermined amount of one or more metal elements selected from magnesium, tin, indium, silver, nickel, zinc, etc., with the balance being copper and unavoidable impurities. The annealed copper wires can be made of tough pitch copper, oxygen-free copper, or the like. In this embodiment, in order to further prevent breakage due to friction between the metal wires, it is preferable to apply liquid paraffin as a lubricant to the surfaces of the second metal wires 42 (for example, the surfaces of the tin-plated annealed copper wires).

[0032] In the cable 1 according to this embodiment, the outer diameter of the second metal wires 42 is larger than the outer diameter of the first metal wires 41. The outer shield layer 4 is subjected to a large load when an external force is applied to the cable 1 or when the cable 1 is bent. In particular, in a cable 1 having a large number of electric wires 2 and a large diameter (outer diameter of 10 mm or more), the weight of the cable 1 (its own weight) applies a load to the outer shield layer 4, which may cause breakage in the metal wires that make up the outer shield layer 4. By making the outer diameter of the second metal wires 42 made of copper or a copper alloy larger than the outer diameter of the first metal wires 41 made of aluminum or an aluminum alloy as in this embodiment, the second metal wires 42, which have higher strength, can withstand a load due to an external force or its own weight, and breakage in the first metal wires 41, which have lower strength, can be prevented.

[0033] Furthermore, the first metal wires 41 made of aluminum or an aluminum alloy are vulnerable to external damage, and when damaged, the damage is likely to cause a breakage of the first metal wires 41 from the damaged point. The sheath 5 is formed by extrusion molding. If the first metal wires 41 are damaged due to interference with surrounding components during the formation of the sheath 5, the damage is likely to cause a breakage of the first metal wires 41 from the damaged point. In contrast, in this embodiment, by making the outer diameter of the second metal wires 42 made of copper or a copper alloy larger than the outer diameter of the first metal wires 41 made of aluminum or an aluminum alloy, the first metal wires 41 are positioned further back than the second metal wires. That is, in the cross section of the cable 1 shown in FIG. 1( a), the outer surfaces of the second metal wires 42 made of copper or a copper alloy (i.e., the surfaces facing the inner surfaces of the sheath 5) tend to protrude radially of the cable 1 from the outer surfaces of the first metal wires 41 made of aluminum or an aluminum alloy (i.e., the surfaces facing the inner surfaces of the sheath 5). As a result, the first metal wires 41 are less likely to be damaged when the sheath 5 is formed, and breaks originating from scratches in the first metal wires 41 are less likely to occur. Furthermore, when an external force is applied to the cable 1 or when the cable 1 is bent, a large load is applied to the outer shield layer 4, and scratches or the like are generated in the first metal wires 41 due to contact between the sheath 5 and the outer shield layer 4, which can prevent breaks in the outer shield layer 4 from occurring as a result of the scratches.

[0034] Furthermore, by making the outer diameter of the second metal wires 42 made of copper or a copper alloy larger than the outer diameter of the first metal wires 41 made of aluminum or an aluminum alloy, the proportion of copper (or copper alloy) in the outer shield layer 4 increases, increasing conductivity and therefore resistance to external noise. To further increase resistance to external noise, the braid density of the outer shield layer 4 is desirably 85% or higher. In this embodiment, the outer diameter of the first metal wires 41 made of aluminum or an aluminum alloy is 0.16 mm, and the outer diameter of the second metal wires 42 made of copper or a copper alloy is 0.18 mm.

[0035] The outer diameter of the first metal wire 41 made of aluminum or an aluminum alloy is, for example, 0.05 mm or more and 0.40 mm or less. The outer diameter of the second metal wire 42 made of copper or a copper alloy is, for example, 0.05 mm or more and 0.40 mm or less. For the first metal wire 41 and the second metal wire 42 having such outer diameters, the outer diameters of the wires 41, 42 are selected so that the outer diameter of the first metal wire 41 is smaller than the outer diameter of the second metal wire 42. In particular, the above-mentioned effects are easily achieved when the outer diameter of the second metal wire 42 is greater than 1.0 times and not greater than 1.2 times the outer diameter of the first metal wire 41.

[0036] (Inner shield layer 8) 1(c), the inner shield layer 8 is made of a braided shield in which multiple third metal wires 81 made of aluminum or an aluminum alloy and multiple fourth metal wires 82 made of copper or a copper alloy are braided together in a crosswise manner, similar to the outer shield layer 4. This allows for a further reduction in the amount of copper used, resulting in a lighter, more flexible cable 1, and also makes it easier to connect the inner shield layer 8 by soldering.

[0037] However, unlike the outer shield layer 4, in the inner shield layer 8, it is desirable that the outer diameter of the third metal wires 81 made of aluminum or an aluminum alloy be larger than the outer diameter of the fourth metal wires 82 made of copper or a copper alloy. This allows the third metal wires 81 made of aluminum or an aluminum alloy, which are relatively easily deformed, to fill the gaps between the metal wires 81, 82, making it possible to further improve resistance to external noise. To further improve resistance to external noise, the braid density of the inner shield layer 8 is desirably at least 85% or more, and is desirably higher than the braid density of the outer shield layer 4.

[0038] In this embodiment, the outer diameter of the third metal wires 81 made of aluminum or an aluminum alloy in the inner shield layer 8 is 0.16 mm, and the outer diameter of the fourth metal wires 82 made of copper or a copper alloy is 0.12 mm. As described above, in this embodiment, the outer diameter of the first metal wires 41 made of aluminum or an aluminum alloy in the outer shield layer 4 is 0.16 mm, and the outer diameter of the first metal wires 41 made of aluminum or an aluminum alloy is equal to the outer diameter of the third metal wires 81. This allows the first metal wires 41 and the third metal wires 81 to be made of the same aluminum or aluminum alloy wire, thereby reducing costs.

[0039] By making the first metal wires 41 and the third metal wires 81 common to each other, the outer diameter of the second metal wires 42 is made larger than the outer diameter of the fourth metal wires 82. Furthermore, the outer diameters of the first metal wires 41 and the third metal wires 81 are made larger than the outer diameter of the fourth metal wire 82 and smaller than the outer diameter of the second metal wire 42. As a result, the following two formulas are satisfied: (Outer diameter of first metal wire 41)<(Outer diameter of second metal wire 42) (Outer diameter of third metal wire 81)>(Outer diameter of fourth metal wire 82) Both of these can be satisfied, making it possible to prevent breakage in the outer shield layer 4 and improve the resistance of the inner shield layer 8 to external noise, while also reducing costs by using a common material for the first metal wires 41 and the third metal wires 81.

[0040] The third metal wire 81 made of aluminum or an aluminum alloy has an outer diameter of, for example, 0.05 mm or more and 0.40 mm or less. The fourth metal wire 82 made of copper or a copper alloy has an outer diameter of, for example, 0.05 mm or more and 0.40 mm or less. For the third metal wire 81 and the fourth metal wire 82 having such outer diameters, the outer diameters of the wires 81, 82 are selected so as to satisfy the above-mentioned condition "outer diameter of the third metal wire 81 > outer diameter of the fourth metal wire 82." In particular, the above-mentioned effect is easily obtained when the outer diameter of the third metal wire 81 is more than 1.0 times and not more than 1.4 times the outer diameter of the fourth metal wire 82.

[0041] (Actions and Effects of the Embodiments) As described above, in the cable 1 according to the present embodiment, the outer shield layer 4 is a braided shield formed by intersecting a plurality of first metal wires 41 made of aluminum or an aluminum alloy with a plurality of second metal wires 42 made of copper or a copper alloy, the outer diameter of the second metal wires 42 being larger than the outer diameter of the first metal wires 41. By using a plurality of first metal wires 41 made of aluminum or an aluminum alloy in the outer shield layer 4, the amount of expensive copper used can be reduced, resulting in a low-cost, lightweight, and easily bendable cable 1. Furthermore, by making the outer diameter of the second metal wires 42 made of copper or a copper alloy larger than the outer diameter of the first metal wires 41 made of aluminum or an aluminum alloy, breakage of the outer shield layer 4 due to external force or its own weight is less likely to occur. The present invention is particularly effective for a large-diameter cable 1 in which a large amount of metal is used in the outer shield layer 4, particularly a cable 1 having an outer diameter of 10 mm or more.

[0042] Conventional composite cables that use only metal wires made of copper or copper alloy for the shielding layer have problems such as difficulty in routing, handling, and transportation when laying the cable due to the cable being difficult to bend and heavy. In contrast, according to the present embodiment, the amount of copper used in the outer shielding layer 4 and the inner shielding layer 8 can be reduced, and by using aluminum or an aluminum alloy that is light and easily deformed, it is possible to realize a lightweight cable 1 that is easy to bend and can be easily processed into a shape suitable for the location where it is to be laid.

[0043] (Other embodiments) In the above embodiment, the cable core 3 has been described as having an inner shielding layer 8, but this is not limiting, and the inner shielding layer 8 can be omitted. For example, as in the cable 1a shown in FIG. 2, the cable core 3 may have a structure in which a plurality of electric wires 2 are twisted together and a pressure winding tape 10 is spirally wound around the twisted electric wires, and the inner shielding layer 8 is not provided. The cable 1a includes a shielding layer 4 that covers the cable core 3, and a sheath 5 that covers the shielding layer 4. As shown in FIG. 1(b), the shielding layer 4 is a braided shield in which a plurality of first metal wires 41 made of aluminum or an aluminum alloy and a plurality of second metal wires 42 made of copper or a copper alloy are braided so as to cross each other, and the outer diameter of the second metal wires 42 is larger than the outer diameter of the first metal wires 41.

[0044] 2, like the cable 1 shown in FIG. 1, the amount of copper used can be reduced and breaks in the shield layer 4 due to the influence of external forces or the cable's own weight can be suppressed. Note that while the cable 1a has a structure in which the filler 6 is provided at the center of the cable, this is not limiting. For example, the filler 6 does not have to be provided at the center of the cable. The electric wire 2 may also be disposed at the center of the cable.

[0045] Furthermore, the electric wires 2 constituting the cable core 3 may include both a signal line for signal transmission and a power line for power supply, and the cable core 3 may be formed by twisting together the signal line and the power line. In FIG. 2, the number of electric wires 2 constituting the cable core 3 is 42, but this is not limited to this. In other words, the number of electric wires 2 constituting the cable core 3 may be one or more. For example, in the case of a structure in which one electric wire 2 is arranged at the center of the cable, a coaxial cable is formed in which a shield layer 4 and a sheath 5 are sequentially provided around the single electric wire 2.

[0046] (Summary of the embodiment) Next, the technical ideas grasped from the above-described embodiments will be described by using the reference numerals and the like in the embodiments. However, the reference numerals and the like in the following description do not limit the components in the claims to the members and the like specifically shown in the embodiments.

[0047] [1] A cable (1) comprising: a cable core (3) having one or more electric wires (2); a shielding layer (4) surrounding the cable core (3); and a sheath (5) surrounding the shielding layer (4), wherein the shielding layer (4) is a braided shield in which a plurality of first metal wires (41) made of aluminum or an aluminum alloy and a plurality of second metal wires (42) made of copper or a copper alloy are braided together so that they cross each other, and the outer diameter of the second metal wires (42) is larger than the outer diameter of the first metal wires (41).

[0048] [2] The cable (1) described in [1], wherein the cable core (3) has an inner shielding layer that covers the electric wires (2) and is provided inside the shielding layer (4), and the inner shielding layer (8) is made of a braided shield in which a plurality of third metal wires (81) made of aluminum or an aluminum alloy and a plurality of fourth metal wires (82) made of copper or a copper alloy are braided together so that they cross each other, and the outer diameter of the third metal wires (81) is larger than the outer diameter of the fourth metal wires (82).

[0049] [3] The cable (1) according to [2], wherein the outer diameter of the second metal wire (42) is larger than the outer diameter of the fourth metal wire (82), and the outer diameters of the first metal wire (41) and the third metal wire (81) are larger than the outer diameter of the fourth metal wire (82) and smaller than the outer diameter of the second metal wire (42).

[0050] [4] The cable (1) according to [2] or [3], wherein the outer diameter of the first metal strand (41) is equal to the outer diameter of the third metal strand (82).

[0051] [5] The cable (1) according to any one of [2] to [4], wherein the braid density of the shielding layer (4) and the inner shielding layer (8) is 85% or more.

[0052] [6] A cable (1) according to any one of [2] to [5], wherein a plurality of the electric wires (2) are arranged between the inner shielding layer (8) and the shielding layer (4).

[0053] [7] The cable (1) according to any one of [1] to [6], wherein the cable core (3) includes, as the electric wire (2), a signal line (21) for signal transmission and a power line (22) for power supply.

[0054] Although the embodiments of the present invention have been described above, the invention according to the claims is not limited to the above-described embodiments. It should be noted that not all of the combinations of features described in the embodiments are necessarily essential to the means for solving the problems of the invention. Furthermore, the present invention can be appropriately modified and implemented within the scope of its spirit. [Explanation of symbols]

[0055] 1...Cable 2...Electric wire 21...Signal line 22…Power line 3...Cable core 3a...Inner core 3b...Outer core 4...Shield layer 41...First metal wire 42…Second metal wire 5...Sheath 8...Inner shield layer 81…Third metal wire 82...Fourth metal wire

Claims

1. a cable core having one or more wires; a shield layer covering the cable core; a sheath that covers the shield layer, the shield layer is made of a braided shield in which a plurality of first metal wires made of aluminum or an aluminum alloy and a plurality of second metal wires made of copper or a copper alloy are braided together so that they cross each other; The outer diameter of the second metal wire is larger than the outer diameter of the first metal wire. cable.

2. the cable core has an inner shield layer that covers the electric wire and is provided inside the shield layer, the inner shield layer is made of a braided shield in which a plurality of third metal wires made of aluminum or an aluminum alloy and a plurality of fourth metal wires made of copper or a copper alloy are braided so as to cross each other, The outer diameter of the third metal wire is larger than the outer diameter of the fourth metal wire. The cable of claim 1 .

3. The outer diameter of the second metal wire is larger than the outer diameter of the fourth metal wire, The outer diameters of the first metal wire and the third metal wire are larger than the outer diameter of the fourth metal wire and smaller than the outer diameter of the second metal wire.

3. The cable of claim 2.

4. The outer diameter of the first metal wire is equal to the outer diameter of the third metal wire.

4. The cable according to claim 2 or 3.

5. The braid density of the shield layer and the inner shield layer is 85% or more. A cable according to any one of claims 2 to 4.

6. A plurality of the electric wires are disposed between the inner shield layer and the shield layer. A cable according to any one of claims 2 to 5.

7. The cable core includes, as the electric wires, a signal line for signal transmission and a power line for power supply. A cable according to any one of claims 1 to 6.

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