Cable

Abstract

To provide a cable capable of suppressing positional deviation of wire due to operation such as flexure and the like and capable of suppressing deterioration of electric property and mechanical property.SOLUTION: The cable 1 includes a central core 2 positioned at the center of the cable, a plurality of first wires (signal wires 3) arranged around the central core 2 along the circumferential direction of the cable, and a sheath 9 that covers the plurality of first wires (signal wires 3). The central core 2 is made of resin and has a hollow cylindrical central portion 21 with a hollow section and a position adjusting portion 22 that covers the central portion 21 and adjusts the positions of the plurality of first wires (signal wires 3) along the circumferential direction of the cable. The position adjusting portion 22 is made of resin and has a tensile strength lower than that of the central portion 21.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] An example of a cable to be wired to a device such as an industrial robot is disclosed in Patent Document 1. The cable described in Patent Document 1 includes a central filler made of a tube placed at the center of the cable, multiple insulated wires placed around the central filler, a pressure winding tape placed around the multiple insulated wires, and a sheath placed around the pressure winding tape. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-172019 Summary of the Invention [Problem to be solved by the invention]

[0004] Devices such as industrial robots have moving parts that are repeatedly bent, twisted, swung, and so on (referred to as bending and other movements), and cables must be routed through these moving parts. In recent years, cables containing many electric wires have been used to accommodate increasingly complex devices and faster signal speeds. When such cables containing many electric wires are routed through moving parts, the center wire is likely to be crushed when the cable is repeatedly subjected to bending and other movements. If the center wire is crushed, the arrangement of the individual electric wires becomes disordered, and repeated bending and other movements while the arrangement of the individual electric wires is disordered can cause kinks and small bends in the electric wire, which can lead to breakage.

[0005] It is possible to prevent the center filler from being crushed by making the center filler out of a relatively hard resin such as nylon, but in this case, when the cable is repeatedly bent or otherwise subjected to motions such as bending, the center filler rubs against the surrounding electric wires, making the wire insulation more susceptible to wear, and there is a risk of a deterioration in electrical and mechanical properties.

[0006] Therefore, an object of the present invention is to provide a cable that can suppress displacement of the wires due to bending or other operations and can suppress deterioration of electrical and mechanical properties. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, the present invention provides a cable comprising a central insert disposed at the center of the cable, a plurality of first electric wires arranged around the central insert in the circumferential direction of the cable, and a sheath covering the plurality of first electric wires, wherein the central insert is made of resin and has a hollow cylindrical center portion with a hollow section, and a position adjustment portion covering the center portion for adjusting the positions of the plurality of first electric wires in the circumferential direction of the cable, and the position adjustment portion is made of resin and has a tensile strength lower than that of the center portion. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a cable that can suppress displacement of electric wires due to bending or other operations and can suppress deterioration of electrical and mechanical properties. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view showing a cross section perpendicular to the longitudinal direction of a cable according to an embodiment of the present invention. [Figure 2] FIG. 10 is a cross-sectional view showing a cross section perpendicular to the longitudinal direction of a cable 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 is a cross-sectional view showing a cross section perpendicular to the longitudinal direction of cable 1 according to this embodiment. Cable 1 is used, for example, as internal wiring in devices such as industrial robots, and is routed through a movable part that repeatedly undergoes bending, twisting, swinging, and other movements (hereinafter referred to as bending and other movements). However, without being limited to this, cable 1 may also be used as wiring for automobiles that repeatedly swings (for example, wiring connecting a device provided on the vehicle body with a device provided on the wheels). Cable 1 can also be used, for example, as wiring for medical equipment or wiring to parts that come into contact with human skin.

[0012] The cable 1 includes a central insert 2, a plurality of signal wires 3 as a plurality of first electric wires, a drain wire 4, a conductive tape 5, a reinforcing layer 6, a plurality of power wires 7 as a plurality of second electric wires, a pressure winding tape 8, and a sheath 9. Each part will be described in detail below.

[0013] (center intervention 2) The cable 1 is repeatedly subjected to bending and other operations, and since the stress caused by bending and other operations is greatest at the center of the cable, it is desirable to place the central filler 2 rather than the signal lines 3 and power lines 7 at the center of the cable. In this embodiment, the central filler 2 has a central portion 21 and a position adjustment portion 22 that covers the central portion 21 and adjusts the positions of the multiple signal lines 3 along the circumferential direction of the cable.

[0014] The center portion 21 is made of a hollow cylindrical resin tube having a hollow portion 21a. The center portion 21 is made of a relatively hard material so as not to be crushed when the signal lines 3 and power lines 7 are twisted together or when the cable 1 is bent. More specifically, the center portion 21 is made of nylon resin, thermoplastic elastomer resin, or polyvinyl chloride resin. This prevents the signal lines 3 from shifting position due to crushing of the center portion 21, suppresses deterioration of electrical characteristics, and prevents breakage due to stress concentration on specific signal lines 3 when the cable 1 is bent or other operations are applied, thereby improving resistance to operations such as bending.

[0015] The outer diameter of the central filler 2 needs to be adjusted to an appropriate value depending on the number of signal lines 3 used. For example, if the central filler 2 is configured only with a center portion 21 made of a resin tube, increasing the thickness of the resin tube to increase the outer diameter of the central filler 2 will make the cable 1 difficult to bend because the center portion 21 is made of a relatively hard material. Also, for example, if the outer diameter is increased while keeping the thickness of the resin tube constant, the rigidity of the center portion 21 will decrease, making the center portion 21 more likely to be crushed. Furthermore, if the central filler 2 is configured only with the center portion 21, because the center portion 21 is made of a relatively hard material, repeated bending or other actions on the cable 1 will cause repeated rubbing between the center portion 21 and the signal lines 3, making the cable more susceptible to breakage.

[0016] Therefore, in this embodiment, a position adjustment portion 22 that is relatively softer than the center portion 21 is provided around the center portion 21. The position adjustment portion 22 is made of a resin that has a lower tensile strength and a lower tensile yield stress than the center portion 21. In this embodiment, the position adjustment portion 22 is made of an inner layer 22a that is an extruded coating layer that covers the center portion 21, and an outer layer 22b that is made of a tape member that covers the inner layer 22a. However, the present invention is not limited to this, and the position adjustment portion 22 may have a single-layer configuration, or may be made of only an extruded coating layer or only a tape member.

[0017] The inner layer 22a formed by extrusion mainly serves to adjust the outer diameter of the central filler 2 while maintaining the bendability of the cable 1 and to provide cushioning properties to prevent wear and misalignment of the signal wires 3 when the cable 1 is bent or otherwise subjected to bending. The tensile strength of the inner layer 22a is preferably 17 MPa to 20 MPa at 23°C. The tensile yield stress of the inner layer 22a is preferably 10 MPa or less. For example, if the center portion 21 is made of nylon resin, the tensile yield stress of the center portion 21 is approximately 40 MPa to 170 MPa. The breaking load of the inner layer 22a is preferably 50 N or more at 23°C. An example of a resin that satisfies these characteristics is polyvinyl chloride resin. Specifically, the inner layer 22a of the position adjustment portion 22 is preferably made of polyvinyl chloride resin. The position adjustment portion 22 may be made of only the inner layer 22a, omitting the outer layer 22b, or the entire position adjustment portion 22 may be made of polyvinyl chloride resin. The tensile strength can be measured by a test method conforming to JIS C 3005, ASTM D 638, or the like.

[0018] The outer layer 22b is a layer for suppressing friction between the inner layer 22a and the signal line 3 and for further improving resistance to movements such as bending. Therefore, it is desirable that the outer layer 22b be made of a material that is softer than the inner layer 22a. The outer layer 22b is not essential and can be omitted. In order to obtain high cushioning properties, it is desirable that the outer layer 22b be made of a foamed resin. In this embodiment, the outer layer 22b is made by wrapping a tape member made of a foamed resin around the inner layer 22a. The tape member made of a foamed resin can be made of a foamed polypropylene resin. The thickness of the tape member is, for example, 200 μm.

[0019] The outer layer 22b is formed by spirally winding a tape member made of foamed resin so that a portion of the tape member overlaps in the width direction. The tape member is preferably wound in the same direction as the twisting direction of the multiple signal wires 3. In other words, the winding direction of the tape member is preferably the same as the twisting direction of the signal wires 3. The winding direction of the tape member is the direction in which the tape member rotates from one end to the other when viewed from one end of the cable 1. The twisting direction of the signal wires 3 is the direction in which the signal wires 3 rotate from one end to the other when viewed from one end of the cable 1.

[0020] If the position adjustment part 22 is too thin, sufficient cushioning may not be obtained, so it is desirable that the thickness of the position adjustment part 22, which is the total thickness of the inner layer 22a and the outer layer 22b, is at least 1.5 mm or more.

[0021] (Signal line 3) The cable 1 has a plurality of signal wires 3 arranged circumferentially around the cable as a plurality of first electric wires. In this embodiment, the plurality of signal wires 3 are twisted in a spiral shape around the central insert 2. While FIG. 1 shows a case in which 24 signal wires 3 are used, the number of signal wires 3 used in the cable 1 is not limited to this. However, the present invention is particularly effective for a multi-core cable 1 using 12 or more signal wires 3.

[0022] In this embodiment, each of the multiple signal wires 3 is composed of a twisted pair 3a formed by twisting a pair of insulated wires 31 together. The insulated wire 31 includes a conductor 31a formed by bunching multiple metal wires together, and an insulator 31b surrounding the conductor 31a. The metal wires constituting the conductor 31a are made of copper or a copper alloy, and their surfaces may be plated with tin, silver, or the like. For example, the conductor 31a may be formed by bunching metal wires made of tin-plated annealed copper wires with an outer diameter of 0.05 mm to 0.10 mm. Note that when the signal wire 3 and the power wire 7 are provided, the outer diameter of the multiple conductors 31a is preferably smaller than the outer diameter of the conductor 7a constituting the power wire 7, which will be described later. Furthermore, the signal wire 3 is not limited to a twisted pair 3a formed by twisting a pair of insulated wires 31 together. For example, the signal wire 3 may be a coaxial wire or the like having an outer conductor and an outer sheath surrounding the insulated wire 31.

[0023] For insulator 31b, a material with a low dielectric constant (preferably a dielectric constant of 3 or less) is preferably used to improve the transmission characteristics of high-speed signals, and resins such as fluororesin (ETFE) (tetrafluoroethylene-ethylene copolymer) or polypropylene or polyethylene are preferably used. In particular, when a large number of signal lines 3 are used, it is desirable to use a thin, moldable fluororesin such as ETFE for insulator 31b in order to prevent the cable 1 from becoming larger in diameter. Note that, if fluororesin is not used from the viewpoint of reducing environmental impact, it is more desirable to use insulator 31b made of polypropylene or cross-linked polypropylene, which has a dielectric constant equivalent to that of fluororesin.

[0024] The signal wires 3 are formed by twisting a pair of insulated wires 31 together and do not have a shielding layer. In order to suppress crosstalk between the signal wires 3, it is advisable to make the twist pitches of the signal wires 3 (twisted pair wires 3a) adjacent to each other in the circumferential direction of the cable different. The twist pitch of the signal wires 3 (twisted pair wires 3a) is the distance along the longitudinal direction of the signal wires 3 between points where the circumferential positions of any insulated wires 31 (the positions in the circumferential direction of the signal wires 3) are the same. In this embodiment, two types of signal wires 3 with different twist pitches are alternately arranged, so that the twist pitches of the signal wires 3 adjacent to each other in the circumferential direction of the cable are different.

[0025] The twisting direction of the twisted pair 3a and the twisting direction of the multiple signal wires 3 are preferably different. If the twisting direction of the twisted pair 3a and the twisting direction of the multiple signal wires 3 were the same, the twisting of the twisted pair 3a would be strengthened by the twisting of the multiple signal wires 3, making it more likely that the insulated wires 31 would break when the cable 1 is repeatedly bent or otherwise subjected to other operations. The twisting direction of the twisted pair 3a is the direction in which the insulated wires 31 rotate from one end to the other when viewed from one end of the twisted pair 3a. The twisting direction of the multiple signal wires 3 is the direction in which the signal wires 3 (twisted pair 3a) rotate from one end to the other when viewed from one end of the cable 1.

[0026] Fluororesin is easily charged by friction. Therefore, if fluororesin is used for the insulator 31b to reduce the diameter of the cable 1, the insulator 31b is easily charged when the cable 1 is repeatedly bent or otherwise subjected to other operations. Furthermore, if a twisted pair wire 3a is used as the signal wire 3, the signal wire 3 has many irregularities on its surface. The insulator 31b is easily charged due to friction between these irregularities and between the irregularities and other components. Furthermore, charging is also generated between the insulated electric wires 31 used in the signal wire 3 due to friction between themselves. Therefore, in a signal wire 3 made of a twisted pair wire 3a, the insulator 31b is more easily charged when the cable 1 is repeatedly bent or otherwise subjected to other operations. To dissipate this charge to ground (i.e., to suppress charging), the conductive tape 5 and drain wire 4, described below, are provided.

[0027] In this embodiment, only a plurality of twisted pairs 3a are twisted around the central insert 2, but this is not limiting, and it is also possible to configure it by winding, for example, a linear body made of resin (for example, a solid linear body with a circular cross section) or an insulated electric wire together.

[0028] (Conductive tape 5 and drain wire 4) The conductive tape 5 is spirally wrapped around the signal lines 3 so as to be in contact with each of the signal lines 3. The conductive tape 5 is a member that serves both to release the electric charge stored on the signal lines 3 to the ground and to act as a shielding layer.

[0029] The conductive tape 5 is a tape member (first tape member) having a substrate and a conductive layer made of a conductive resin provided on the surface of the substrate. The substrate is made of a resin such as a polyolefin resin as a base resin and is formed in a long, strip-like shape. The substrate has a first surface and a second surface facing each other in a thickness direction perpendicular to the longitudinal direction of the substrate. The conductive layer is provided in a laminated state so as to cover at least one of the surfaces (first surface and second surface) of the substrate. The conductive layer is made of a conductive resin whose base resin is a resin such as a polyolefin resin and in which conductive particles are dispersed. The conductive tape 5 is spirally wrapped around the multiple signal wires 3 with the conductive layer in contact with the signal wires 3. The base resins constituting the substrate and the conductive layer may contain additives such as a crosslinking agent, a crosslinking catalyst, an antioxidant, a plasticizer, a lubricant, a filler, a flame retardant, a stabilizer, and a colorant. The substrate may also be conductive.

[0030] In this embodiment, an olefin-based resin, which has a low dielectric constant and can improve electrical properties, is used as the base resin of the tape member constituting the conductive tape 5. More specifically, the base resin of the substrate constituting the tape member is made of an olefin-based resin, and the conductive layer constituting the tape member is made of a conductive resin in which conductive fine particles are dispersed in a base resin made of an olefin-based resin. This allows the conductive tape 5 to perform the above-mentioned functions while maintaining the softness (flexibility and pliability that allows it to flex easily when bent) of a tape member. For example, PP or PE can be used as the olefin-based resin. Carbon fine particles can be used as the conductive fine particles. The conductive tape 5 is spirally wound so that portions of the tape overlap in the width direction. The winding direction of the conductive tape 5 is preferably the same as the twisting direction of the signal wires 3. This makes the cable 1 easier to bend and improves its bending resistance.

[0031] The tape member constituting the conductive tape 5 is an extrusion molded product in which a conductive layer is laminated on one or both surfaces (first and second surfaces) of the substrate by simultaneously extruding a resin constituting the substrate and a conductive resin constituting the conductive layer using an extruder. It is particularly preferable to use the same olefin-based resin for both the base resin constituting the substrate and the base resin constituting the conductive layer. This enhances the adhesion at the interface between the substrate and the conductive layer. Therefore, even if the cable 1 is subjected to repeated bending or other operations, peeling or other problems can be suppressed at the interface between the substrate and the conductive layer, and the functionality of the conductive tape 5 is less likely to deteriorate. It is also preferable to provide a conductive layer on both the first and second surfaces of the substrate. This makes it easier to simultaneously discharge the electric charge on the signal line 3 to ground and function as a shielding layer.

[0032] The conductive tape 5 preferably has an overall thickness (thickness of the tape member) of 90 μm or more and 150 μm or less. More preferably, the thickness of the conductive tape 5 is 90 μm or more and 150 μm or less and is smaller than the thickness of the insulator 31b. When the conductive tape 5 has an overall thickness of 90 μm or more, the conductive tape 5 is less likely to break when the cable 1 is bent or twisted. Furthermore, when the conductive tape 5 has an overall thickness of 150 μm or less, other components (such as the signal line 3) that come into contact with the conductive tape 5 are less likely to be damaged when the cable 1 is bent or twisted. Therefore, by ensuring that the overall thickness of the conductive tape 5 is within the above-mentioned range, the cable 1 can be more resistant to bending or twisting. In this case, the thickness of the substrate constituting the tape member is preferably greater than the thickness of the conductive layer provided on one surface of the substrate. For example, the thickness of the substrate is preferably at least twice the thickness of the conductive layer. More preferably, the thickness of the substrate is at least two times but not more than three times the thickness of the conductive layer. When a conductive layer is laminated on each of the surfaces (both surfaces) of the substrate, the thickness of the substrate is preferably greater than the thickness of the conductive layer provided on one surface of the substrate and greater than the total thickness of the conductive layers provided on both surfaces of the substrate. In addition, in order to have good shielding performance (noise suppression effect) in the frequency band of 0.1 MHz to 100 MHz, the surface resistance of the conductive tape 5 is 1.0 × 10 6 Ω greater than 3.0×10 6 Ω or less, preferably 1.2×10 6 Ω or more 2.0×10 6 It is preferable that it is Ω or less.

[0033] The winding direction of the conductive tape 5 is preferably the same as the twisting direction of the multiple signal wires 3. This makes it difficult for the twisting of the multiple signal wires 3 to loosen. The winding direction of the conductive tape 5 is the direction in which the conductive tape 5 rotates from one end to the other end of the cable 1 when viewed from one end of the cable 1.

[0034] The conductive tape 5 is composed of a tape member having a non-conductive substrate made of an olefin-based resin and a conductive layer formed on the surface of the substrate and made of a conductive resin in which conductive particles are dispersed in an olefin-based resin. This provides the flexibility of a tape member (i.e., flexibility and pliability that allows the tape to flex flexibly when bent) and prevents degradation of conductivity due to friction with the signal line 3. Therefore, even if the cable 1 is subjected to repeated bending or other operations, the signal line 3 (insulator 31b) is less likely to wear due to friction with the conductive tape 5, and degradation of electrical characteristics can be suppressed. For example, instead of the conductive tape 5, a metal tape such as a copper-PET tape, in which a copper layer is formed on one side of a resin tape made of PET (polyethylene terephthalate), may be used. However, if a metal tape is used instead of the conductive tape 5, due to its hardness, when the cable 1 is subjected to repeated bending or other operations, the edge of the metal tape may rub against the insulator 31b, causing the insulator 31b to be worn away, which may significantly reduce the durability against bending or other operations. Furthermore, for example, if a copper-plated tape made by plating a cloth body with copper is used instead of the conductive tape 5, the wear of the insulator 31b can be suppressed, but the copper plating is likely to peel off due to friction with the signal line 3, which may reduce the shielding performance and result in reduced electrical characteristics.

[0035] It is more preferable to use conductive tape 5 having conductive layers on both sides of the substrate, so that when conductive tape 5 is wound spirally so that parts of it overlap in the width direction, the conductive layers on the front and back sides come into contact with each other, forming a continuous conductive layer in the longitudinal direction, which contributes to improving electrical properties.

[0036] The drain wire 4 serves to ground the conductive tape 5. Since it is difficult to connect the conductive tape 5 to a ground line by soldering during terminal processing and it is not easy to ground the conductive tape 5, in this embodiment, the drain wire 4 is used to facilitate terminal processing. The drain wire 4 is arranged between a pair of signal wires 3 adjacent to each other in the circumferential direction of the cable and the conductive tape 5, among the multiple signal wires 3, so as to be in contact with the conductive tape 5. In this embodiment, the drain wire 4 is twisted spirally together with the multiple signal wires 3, and the conductive tape 5 is wrapped around it.

[0037] The drain wire 4 is a stranded conductor formed by twisting together multiple metal wires. The metal wires constituting the drain wire 4 are made of copper or a copper alloy, and their surfaces may be plated with tin, silver, or the like. The drain wire 4 may be formed, for example, as a concentrically twisted wire formed by concentrically twisting multiple metal wires made of tin-plated annealed copper wires with an outer diameter of 0.05 mm to 0.10 mm, or as a bunched twisted wire formed by bunching multiple metal wires. The drain wire 4 has a smaller outer diameter than the signal wires 3 and is arranged so as to fit into the valleys between adjacent signal wires 3 in the circumferential direction of the cable. In particular, the drain wire being a bunched twisted wire allows the cross-sectional shape of the drain wire to be deformed into a non-circular shape, such as an ellipse, and also makes it easier to fit into the valleys between adjacent signal wires 3 in the circumferential direction of the cable. This reduces the likelihood of unevenness on the surface of the conductive tape 5, and reduces the likelihood of the cross-sectional shape of the cable 1 becoming distorted in the circumferential direction of the cable. If the cross-sectional shape of cable 1 is less likely to become distorted, stress can be prevented from concentrating locally on distorted parts when repeated bending, twisting, etc. is applied, and resistance to repeated bending, twisting, etc. is less likely to decrease.

[0038] (Reinforcing layer 6) The reinforcing layer 6 is provided between the conductive tape 5 and the multiple power wires 7, and serves to protect the relatively soft conductive tape 5 from being crushed by the radially inward pressing force that is applied when the multiple power wires 7 are twisted together. The reinforcing layer 6 also serves to protect the conductive tape 5 from being damaged by friction between the conductive tape 5 and the power wires 7 when the cable 1 is subjected to repeated bending or other operations.

[0039] The reinforcing layer 6 may be a layer formed by extrusion molding. However, in this case, the reinforcing layer 6 becomes a cylindrical molded body, making it difficult to bend the cable 1. Forcibly bending the cable 1 may cause the reinforcing layer 6 to break. Therefore, from the viewpoint of making the cable 1 easier to bend, the reinforcing layer 6 is preferably formed by spirally winding a tape member (second tape member) made of resin around the conductive tape 5. By forming the reinforcing layer 6 from a tape member, the winding of the conductive tape 5 and the winding of the tape member of the reinforcing layer 6 can be performed in a single process, thereby reducing manufacturing costs. The winding direction of the tape member constituting the reinforcing layer 6 is preferably the same as the winding direction of the conductive tape 5. This makes it difficult for the winding of the conductive tape 5 to loosen.

[0040] Examples of tape members that can be used for the reinforcing layer 6 include resin tapes made of non-foamed resins such as polyethylene, polypropylene, and polyvinyl chloride; foamed resin tapes made of foamed resins such as foamed polypropylene; and nonwoven fabrics. It is more desirable to use foamed resin tapes to improve cushioning properties and thereby enhance the protective performance of the conductive tape 5. To further enhance the protective performance of the conductive tape 5, the tape members used for the reinforcing layer 6 should be at least thicker than the conductive tape 5. More specifically, the thickness of the tape members used for the reinforcing layer 6 should be greater than one time and not more than three times the thickness of the conductive tape 5. The reinforcing layer 6 may be omitted.

[0041] For further reinforcement, the reinforcing layer 6 may be composed of two tape members. More specifically, the reinforcing layer 6 may be configured such that a foamed resin tape is spirally wound as the first tape member, and then a resin tape other than the foamed resin tape or a nonwoven fabric is spirally wound around the first tape member. In this case, the tape member provided on the inner side in the cable radial direction should be thicker than the tape member provided on the outer side in the cable radial direction, for example, between two and four times the thickness of the outer tape member.

[0042] (power line 7) A plurality of power wires 7 are wound around the reinforcing layer 6 in the circumferential direction of the cable as a plurality of second electric wires. Here, a case where 36 power wires 7 are used is shown, but the number of power wires 7 is not limited to this. The power wires 7 have a conductor 7a made of a bunched stranded wire formed by bunching a plurality of metal wires together, and an insulator 7b covering the conductor 7a. The metal wires that make up the conductor 7a are made of copper or a copper alloy, and their surfaces may be plated with tin, silver, or the like. The conductor 7a can be formed, for example, by bunching a plurality of metal wires made of tin-plated annealed copper wires having an outer diameter of more than 0.10 mm.

[0043] The twisting direction of the power wires 7 is preferably the same as the twisting direction of the signal wires 3. This makes the cable 1 easier to bend and improves its resistance to movements such as bending. The power wires 7 are not essential and can be omitted. If the power wires 7 are omitted, the reinforcing layer 6 can also be omitted. Furthermore, only signal wires may be twisted around the reinforcing layer 6 in place of the power wires 7, or both the power wires 7 and signal wires may be twisted together.

[0044] In the cable 1, the multiple power lines 7 (multiple second electric wires) do not have to be arranged radially outward of the conductive tape 5. In this case, the cable 1 has a sheath 9 provided around the conductive tape 5 or the reinforcing layer 6 in contact with the conductive tape 5 or the reinforcing layer 6. In addition, in the cable 1, the multiple power lines 7 and the multiple signal lines 3 may be arranged in a mixed manner along the circumferential direction of the cable radially outward of the conductive tape 5.

[0045] (Pressing tape 8) The pressure wrapping tape 8 serves to prevent the power wires 7 from untwisting. The pressure wrapping tape 8 can be a resin tape made of, for example, PE or PP. The pressure wrapping tape 8 is spirally wrapped around the multiple power wires 7 so that portions of the pressure wrapping tape overlap in the width direction. The winding direction of the pressure wrapping tape 8 is preferably the same as the winding direction of the conductive tape 5. When signal wires 3 are used instead of the power wires 7 outside the conductive tape 5 in the cable radial direction, or when power wires 7 and signal wires 3 are mixed, a conductive tape may be used as the pressure wrapping tape 8 to suppress static buildup. In this case, it is desirable to also provide a drain wire for grounding the conductive tape. The thickness of the tape material used for the reinforcing layer 6 is preferably thicker than the pressure wrapping tape 8, for example, between two and four times the thickness of the pressure wrapping tape 8. The thickness of the pressure wrapping tape 8 is preferably equal to or less than the thickness of the conductive tape 5. Furthermore, if the power line 7 is not provided radially outward of the conductive tape 5, the pressure winding tape 8 can be omitted.

[0046] (Sheath 9) The sheath 9 is provided to cover the periphery of the pressure wrapping tape 8. The sheath 9 is made of a resin composition primarily composed of, for example, PVC, silicone rubber, chlorinated polyethylene, or the like. For applications requiring chemical resistance or applications involving contact with human skin, a resin composition primarily composed of silicone rubber is preferably used. The resin composition may contain additives such as a crosslinking agent, a crosslinking catalyst, an antioxidant, a plasticizer, a lubricant, a filler, a flame retardant, a stabilizer, and a colorant. The surface of the sheath 9 may be provided with a coating to improve the slipperiness of the surface of the sheath 9. In particular, when the sheath 9 is made of a resin composition primarily composed of silicone rubber, it is preferable to provide a coating to improve the slipperiness of the surface. The coating provided on the surface of the sheath 9 may be, for example, a liquid silicone rubber containing fine particles with an average particle diameter of 1 μm to 10 μm, which is cured by an addition reaction. The fine particles may be made of, for example, silicone rubber, silicone resin, or the like. The thickness of the coating is, for example, 3 μm or more and 100 μm or less. The static friction coefficient of the surface of the coating is 0.5 or less. The sheath 9 is preferably separated from the underlying member by a small gap or the like. This prevents the sheath 9 from deteriorating due to friction with the underlying member caused by bending or other operations.

[0047] (Actions and Effects of the Embodiments) As described above, in the cable 1 according to this embodiment, the central insert 2 has a central portion 21 and a position adjustment portion 22 that covers the central portion 21 and adjusts the positions of the multiple signal lines 3 along the circumferential direction of the cable, and the position adjustment portion 22 has a lower tensile strength than the central portion 21.

[0048] By adjusting the outer diameter of the central filler 2 using the position adjustment portion 22, which is softer (has lower tensile strength) than the center portion 21, it is possible to suppress misalignment of the signal wires 3 while maintaining the ease of bending of the cable 1. As a result, it is possible to suppress problems such as a decrease in electrical characteristics due to misalignment and wire breakage due to stress concentration, and it is possible to improve the cable 1's resistance to bending and other operations. Furthermore, because the outer periphery of the central filler 2 can be made of a relatively soft material, it is possible to suppress wear of the signal wires 3 due to friction when the cable 1 is repeatedly bent and other operations, and it is possible to further improve the cable 1's resistance to bending and other operations. As such, according to this embodiment, it is possible to realize a cable 1 that can suppress misalignment of the signal wires 3 due to bending and other operations, and that can suppress deterioration of the electrical and mechanical characteristics. Note that in a cable 1 in which multiple second electric wires (power wires 7) are provided around multiple first electric wires (signal wires 3), the above-mentioned effects are more likely to be achieved when the number of insulated electric wires 31 constituting the first electric wires (signal wires 3) is greater than the number of second electric wires (power wires 7).

[0049] (Other embodiments) Fig. 2 is a cross-sectional view perpendicular to the longitudinal direction of a cable 1a according to another embodiment of the present invention. The cable 1a shown in Fig. 2 uses a braided layer 12 instead of the conductive tape 5. The braided layer 12 has a relatively large metal volume, and is therefore suitable for improving shielding performance at relatively low frequencies (for example, a frequency band of 0.1 MHz to 100 MHz).

[0050] The braided layer 12 covers the signal wires 3 to act as a shield that suppresses noise, and also acts as a cushioning layer that relieves radially inward pressure on the signal wires 3. In the cable 1a, the braided layer 12 is made of an interwoven braid in which metal wires and fiber wires are braided. By forming the braided layer 12 from an interwoven braid, cushioning properties can be imparted to the braided layer 12, which relieves radially inward pressure on the signal wires 3 and improves resistance to movements such as bending.

[0051] The metal wires used in the braided layer 12 may be made of copper or a copper alloy, and their surfaces may be plated with tin, silver, or the like. Here, tin-plated annealed copper wires are used as the metal wires. Staple fiber yarns, nylon yarns, or the like can be used as the fiber wires used in the braided layer 12. The braid angle (the angle between the longitudinal direction of the metal wires and fiber wires and the longitudinal direction of the cable) of the interwoven braid constituting the braided layer 12 is preferably 40 degrees or more. This reduces the size of the holes between the metal wires and fiber wires, thereby further enhancing cushioning properties. For example, in a braided shield using only metal wires, a braid angle of 40 degrees or more makes the braided layer 12 very stiff, making the cable 1 difficult to bend. By using an interwoven braid for the braided layer 12 in this embodiment, sufficient flexibility can be maintained even when the braid angle is 40 degrees or more, thereby enhancing cushioning properties and making the cable 1 easier to bend.

[0052] Here, the braided layer 12 is formed of a mixed weave braid, but the braided layer 12 may also be formed by braiding metal foil yarns in which metal foil is wrapped around fiber yarns. For example, the braided layer 12 can be formed using copper foil yarns in which copper foil is wrapped around staple fiber yarns. By using metal foil yarns for the braided layer 12, it is possible to impart cushioning properties to the braided layer 12 and maintain the flexibility of the cable 1, just as in the case of a mixed weave braid.

[0053] If the braided layer 12 were to come into direct contact with the signal wires 3 or the power wires 7, repeated bending or other operations of the cable 1 could cause friction and breakage in the metal wires or fiber wires that make up the braided layer 12. To prevent such problems, the cable 1 is provided with an inner tape member 10 between the signal wires 3 and the braided layer 12, and an outer tape member 11 between the braided layer 12 and the power wires 7.

[0054] The inner tape member 10 is spirally wound around the signal wire 3 so that portions of the inner tape member 10 overlap with each other in the width direction. The outer tape member 11 is spirally wound around the braided layer 12 so that portions of the outer tape member 11 overlap with each other in the width direction. To further reduce the radially inward pressure on the signal wire 3, it is preferable to use materials with cushioning properties for the inner tape member 10 and the outer tape member 11. Specifically, the inner tape member 10 and the outer tape member 11 can be made of nonwoven fabric, paper, resins such as nylon and fluororesin, or foamed resin. Of these, nonwoven fabric or foamed resin is particularly preferable for enhancing cushioning properties. Foamed polypropylene, for example, can be used as the foamed resin. The thickness of the inner tape member 10 and the outer tape member 11 should preferably be 50 μm or more and 100 μm or less. The inner tape member 10 and the outer tape member 11 should preferably be made of the same material. For example, if the inner tape member 10 is made of nonwoven fabric, it is preferable that the outer tape member 11 is also made of nonwoven fabric. It is also preferable that the inner tape member 10 and the outer tape member 11 have the same thickness. This makes it possible to use the same tape for the inner tape member 10 and the outer tape member 11, thereby improving the productivity of the cable 1.

[0055] The winding direction of the inner tape member 10 is preferably the same as the twisting direction of the signal wires 3. This makes it difficult for the twisting of the signal wires 3 to become loose. Similarly, the winding direction of the outer tape member 11 is preferably the same as the twisting direction of the power wires 7. This makes it difficult for the winding of the outer tape member 11 to become loose. The winding direction of the inner tape member 10 or the outer tape member 11 is the direction in which the inner tape member 10 or the outer tape member 11 rotates from one end to the other when viewed from one end of the cable 1. The twisting direction of the signal wires 3 or the power wires 7 is the direction in which the signal wires 3 or the power wires 7 rotate from one end to the other when viewed from one end of the cable 1. Here, the twisting direction of the signal wires 3, the winding direction of the inner tape member 10, the winding direction of the outer tape member 11, and the twisting direction of the power wires 7 are all assumed to be the same direction.

[0056] (Variation) In the above embodiment, the position adjustment section 22 has a two-layer structure, but it may have a one-layer structure or a three-layer or more structure. Also, the center section 21 does not have to be hollow cylindrical, and may be solid.

[0057] Furthermore, a mixture of signal wires 3 and power wires 7 may be arranged as a plurality of first electric wires radially inward of the conductive tape 5. The plurality of first electric wires may be, for example, a combination of signal wires 3 and power wires 7 arranged along the circumferential direction of the cable radially inward of the conductive tape 5, a combination of a plurality of power wires 7 arranged so as to surround the outer periphery of a plurality of signal wires 3 arranged along the circumferential direction of the cable, or a combination of a power wire 7 arranged inside a plurality of signal wires 3 arranged along the circumferential direction of the cable.

[0058] In addition, in the above embodiment, a plurality of signal lines 3 are arranged along the circumferential direction of the cable as a plurality of first electric wires radially inward of the conductive tape 5, but instead of the plurality of signal lines 3, a plurality of power supply lines 7 may be arranged along the circumferential direction of the cable.

[0059] In the above embodiment, in the plurality of first electric wires and the plurality of second electric wires arranged along the circumferential direction of the cable, intervening members made of resin strings, fiber threads, etc. may be arranged between the electric wires to fill gaps between adjacent electric wires. When a plurality of intervening members are arranged, it is preferable that the intervening members made of the same material are arranged at equal intervals along the circumferential direction of the cable.

[0060] (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.

[0061] [1] A cable (1) comprising: a central insert (2) arranged at the center of the cable; a plurality of first electric wires (signal wires 3) arranged around the central insert (2) in the circumferential direction of the cable; and a sheath (9) covering the plurality of first electric wires (signal wires 3), wherein the central insert (2) is made of resin and has a hollow cylindrical center portion (21) having a hollow section, and a position adjustment portion (22) covering the center portion (21) for adjusting the positions of the plurality of first electric wires (signal wires 3) in the circumferential direction of the cable, and the position adjustment portion (22) is made of resin and has a lower tensile strength than the center portion (21).

[0062] [2] The cable according to [1], wherein the position adjustment portion (22) is made of polyvinyl chloride resin.

[0063] [3] The cable (1) according to [1], wherein the core (21) is made of nylon resin, thermoplastic elastomer resin, or polyvinyl chloride resin.

[0064] [4] The cable (1) described in [1], wherein the position adjustment portion (22) comprises at least an inner layer (22a) covering the center portion (21) and an outer layer (22b) covering the inner layer (22a), and the outer layer (22b) is made of a foamed resin.

[0065] [5] The cable (1) according to [4], wherein the outer layer (22b) is formed by wrapping a tape member made of the foamed resin around the inner layer (22a).

[0066] [6] The cable (1) according to [5], wherein the tape member is made of a foamed polypropylene resin.

[0067] [7] The cable (1) according to [5], wherein the tape member is wound in the same direction as the twisting direction of the plurality of first electric wires (signal wires 3).

[0068] [8] The cable (1) described in [1] has a conductive tape (5) wrapped around the plurality of first electric wires (signal wires 3) between the plurality of first electric wires (signal wires 3) and the sheath (9), and the conductive tape (5) has a base material and a conductive layer made of a conductive resin provided on the surface of the base material.

[0069] [9] The cable (1a) according to [1], having a braided layer (12) between the plurality of first electric wires (signal wires 3) and the sheath (9), the braided layer (12) being made of an interwoven braid in which a plurality of metal wires and a plurality of fiber wires are braided.

[0070]

[10] The cable (1a) according to [1], having a braided layer (12) between the plurality of first electric wires (signal wires 3) and the sheath (9), the braided layer being made of metal foil threads in which metal foil is wrapped around fiber threads.

[0071]

[11] The cable (1) described in [1], wherein the plurality of first electric wires (signal wires 3) have a conductor (31a) and an insulator (31b) made of fluororesin, polypropylene, or cross-linked polypropylene that covers the conductor (31a).

[0072] (Addendum) 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]

[0073] 1...Cable 2…Central intervention 21…Center 21a...Hollow part 22...Position adjustment section 22a...inner layer 22b…outer layer 3...Signal line 4...Drain wire 5...Conductive tape 6...Reinforcement layer 7…Power line 8...Press and wrap tape 9...Sheath

Claims

1. a central filler disposed at the center of the cable; a plurality of first electric wires arranged around the central interposer along a circumferential direction of the cable; a sheath that covers the plurality of first electric wires, the central interposer is made of resin and has a hollow cylindrical central portion having a hollow portion, and a position adjustment portion that covers the central portion and adjusts positions of the plurality of first electric wires in a cable circumferential direction, the position adjustment portion is made of resin and has a lower tensile strength than the center portion; cable.

2. The position adjustment portion is made of polyvinyl chloride resin. The cable of claim 1 .

3. the core is made of nylon resin, thermoplastic elastomer resin, or polyvinyl chloride resin; The cable of claim 1 .

4. the position adjustment portion includes at least an inner layer covering the center portion and an outer layer covering the inner layer, The outer layer is made of a foamed resin. The cable of claim 1 .

5. The outer layer is configured by wrapping a tape member made of the foamed resin around the inner layer.

5. The cable of claim 4.

6. The tape member is made of a foamed polypropylene resin.

6. The cable of claim 5.

7. The tape member is wound in the same direction as the twisting direction of the plurality of first electric wires.

6. The cable of claim 5.

8. a conductive tape is provided between the plurality of first electric wires and the sheath and is wound around the plurality of first electric wires; The conductive tape has a substrate and a conductive layer made of a conductive resin provided on a surface of the substrate. The cable of claim 1 .

9. a braided layer formed by interwoven braiding a plurality of metal wires and a plurality of fiber wires is provided between the plurality of first electric wires and the sheath; The cable of claim 1 .

10. A braided layer is provided between the plurality of first electric wires and the sheath, the braided layer being formed by braiding metal foil threads in which metal foil is wrapped around fiber threads. The cable of claim 1 .

11. The plurality of first electric wires each include a conductor and an insulator covering the conductor, the insulator being made of fluororesin, polypropylene, or cross-linked polypropylene. The cable of claim 1 .

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