Cable

Abstract

To provide a cable capable of realizing excellent mechanical characteristic difficult to generate troubles such as disconnection when repeatedly bent, and excellent transmission characteristics capable of transmitting a large volume data.SOLUTION: A cable 1 includes a plurality of paired twisted wires 3 composed by twisting a pair of wires 31 having an insulator 31b around a conductor 31a, an intervention 4 composed of a plurality of synthetic fibers arranged around the plurality of paired strands 3, a tape member 61 wound spirally around an aggregate 5 obtained by twisting a plurality of paired strands 3 and intervention 4, and a sheath 8 covering an outer circumference of the tape member 61. The tape member 61 has a friction coefficient of its surface smaller than the friction coefficient of a surface of the insulator 31b, and the synthetic fiber has a tensile strength of 49 N or more and an elongation of 15% or more.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a cable.

Background Art

[0002] In recent years, as a measure to improve productivity, the market for human-collaborative robots and small articulated robots has been expanding. As robot cables used for such robots, a cable for a movable part wired to a movable part of the robot and a cable for a fixed part connecting the robot and a control device are used.

[0003] Note that as prior art document information related to the invention of this application, there is Patent Document 1.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In recent years, high-quality cameras and the like have been used in the above-described robots, and it has been required that large-capacity data communication be possible also in robot cables. In particular, in a cable for a movable part wired to a movable part of a robot, it is required to realize excellent transmission characteristics enabling large-capacity data communication while realizing excellent mechanical characteristics in which problems such as disconnection hardly occur when repeatedly bent.

[0006] Therefore, an object of the present invention is to provide a cable capable of realizing excellent mechanical characteristics in which problems such as disconnection hardly occur when repeatedly bent and excellent transmission characteristics enabling large-capacity data communication.

Means for Solving the Problems

[0007] The present invention aims to solve the above problems, and provides a cable comprising: a tensile strength wire made of tensile strength fibers arranged at the center of the cable; a plurality of pair-twisted wires formed by twisting a pair of electric wires and twisted around the tensile strength wire; an intervening layer made of a plurality of synthetic fibers arranged around the pair-twisted wires; a wear suppression layer formed by spirally winding a tape member around the aggregate obtained by twisting the plurality of pair-twisted wires and the intervening layer around the tensile strength wire; a shield layer made of a braided shield covering the outer periphery of the wear suppression layer; and a sheath covering the periphery of the shield layer. The wear suppression layer is configured such that the surface facing the aggregate of the tape member and the surface facing the shield layer are made of a fluororesin, and the tape member is non-adhesively overlapped so that a part of the width direction of the tape member overlaps.

Advantages of the Invention

[0008] According to the present invention, it is possible to provide a cable capable of realizing excellent mechanical characteristics in which problems such as disconnection are unlikely to occur when repeatedly bent, and excellent transmission characteristics enabling large-capacity data communication.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0010] [Embodiment] Hereinafter, embodiments 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 the cable according to the present embodiment. The cable 1 is used, for example, for internal or external wiring of a robot used in a factory or the like, or for wiring under a spring in an automobile (that is, wiring connecting a device provided on a wheel (for example, a braking device or sensors) and a device provided on a vehicle body (for example, a control device)), and at least a part of it is disposed across a movable part or a swinging part. Further, the cable 1 is used as a communication cable (so-called LAN cable) for transmitting signals such as image signals. The cable 1 is, for example, a Category 5e LAN cable.

[0012] As shown in FIG. 1, the cable 1 includes a tensile strength wire 2, a plurality of twisted pairs 3, an interlayer 4, a wear suppression layer 6 provided around an aggregate 5 formed by twisting a plurality of twisted pairs 3 and the interlayer 4 around the tensile strength wire 2, a shield layer 7 composed of a braided shield covering the outer periphery of the wear suppression layer 6, and a sheath 8 covering the periphery of the shield layer 7.

[0013] (Tensile strength wire 2) The tensile strength wire 2 bears the tension applied to the cable 1 when the cable 1 is repeatedly bent, and serves to prevent the other members such as the twisted pair 3 and the shield layer 7 from being loaded by the tension. The tensile strength wire 2 is made of a tensile strength fiber and is disposed at the center of the cable 1. As the tensile strength fiber used for the tensile strength wire 2, aramid fiber or the like can be used. In order for the tensile strength wire 2 to sufficiently bear the tension applied to the cable 1, the elongation of the tensile strength fiber used for the tensile strength wire 2 is smaller than the elongation of the conductor 31a of the electric wire 31 constituting the twisted pair 3 (10% or more in the present embodiment), the elongation of the insulator 31b (150% or more in the present embodiment), and the elongation of the metal strand constituting the shield layer 7 (7% or more and less than 15% in the present embodiment). More specifically, it is preferably less than 3%.

[0014] In this embodiment, the tensile line 2 is formed using a plurality of tensile fibers made of aramid fibers with a fineness of 1420 denier. Note that 1 denier refers to a fiber with a length of 450 m and a mass of 0.05 g. The tensile fibers constituting the tensile line 2 preferably have a larger fineness than the synthetic fibers (such as nylon fibers) constituting the intervening member 4 described later in order to reduce the occurrence of problems such as wire breakage when the cable 1 is repeatedly bent.

[0015] Also, in order to effectively burden the tensile line 2 with the tension when the cable 1 is repeatedly bent, it is desirable to arrange the tensile fibers (here, aramid fibers) constituting the tensile line 2 straight along the cable longitudinal direction. The tensile strength of the tensile fibers used for the tensile line 2 is preferably 2900 MPa or more and 3400 MPa or less. Also, the moisture content of the tensile fibers used for the tensile line 2 is preferably 3.5% or more and 7.0% or less, and the density is 1.4 g / cm 3 to 1.5 g / cm 3 or less.

[0016] (Twisted pair line 3) The twisted pair line 3 is formed by twisting a pair of electric wires 31. The electric wire 31 has a conductor 31a and an insulator 31b that covers the periphery of the conductor 31a. In order to enhance the durability against bending, as the conductor 31a, it is preferable to use a stranded conductor formed by collectively stranding a plurality of metal strands. The outer diameter of the conductor 31a is preferably, for example, 0.30 mm to 3.00 mm in order to enhance the durability against bending. In this embodiment, a conductor 31a with an outer diameter of 0.50 mm formed by collectively stranding 30 metal strands made of a tinned soft copper wire with an outer diameter of 0.08 mm is used.

[0017] In order to reduce the diameter of the cable 1, it is desirable that the thickness of the insulator 31b be as thin as possible. For example, it is preferably about 0.10 mm to 0.30 mm. As the insulator 31b, it is advisable to use a thin-wall and extrudable fluororesin. Examples of the fluororesin used for the insulator 31b include FEP (perfluoroethylene propylene copolymer) and PFA (perfluoroalkoxyalkane). Also, PP (polypropylene) may be used as the insulator 31b. In this embodiment, an insulator 31b made of FEP with a thickness of about 0.25 mm is used, and the outer diameter of the electric wire 31 is set to about 1.00 mm. The outer diameter of the pair-twisted wire 3 formed by twisting a pair of electric wires 31 is about 2.00 mm.

[0018] The insulator 31b is preferably formed by tube extrusion around the conductor 31a. Thereby, the conductor 31a can move in the longitudinal direction of the electric wire 31 within the insulator 31b, and it becomes difficult for the conductor 31a to break when the cable 1 is bent.

[0019] In order to realize transmission characteristics enabling large-capacity data communication and improve the transmission characteristics of high-frequency signals (more specifically, for example, to make it difficult for high-frequency signals in the band of 1 MHz to 6 GHz to attenuate during long-distance transmission), it is desirable to use an insulator 31b with as low a dielectric constant as possible. For example, as the insulator 31b, a three-layer structure having an unfilled extrusion layer provided by tube extrusion using a low-dielectric constant non-foamed resin material on the outer periphery of the conductor 31a, a foamed layer provided non-adhesively on the outer periphery of the unfilled extrusion layer, and a non-foamed layer provided adhesively on the outer periphery of the foamed layer may be used. As the unfilled extrusion layer, for example, a fluororesin material such as FEP or PFA can be used. Also, for the foamed layer, it is advisable to use a resin material with a lower melting point than the resin material used for the unfilled extrusion layer. For example, those made of irradiated crosslinked foamed polyethylene, foamed polypropylene, etc. can be used. Furthermore, the non-foamed layer is preferably made of the same resin material as the foamed layer. For example, those made of non-foamed polypropylene, irradiated crosslinked polyethylene, etc. can be used.

[0020] Cable 1 includes four twisted pairs 3 formed by twisting a pair of electric wires 31 together. These four twisted pairs 3 and the intervening member 4 described later are twisted around the tension-resistant wire 2 to form an assembly 5. Note that the number of twisted pairs 3 used in the assembly 5 is not limited to four. Also, in this embodiment, all the twisted pairs 3 constituting the assembly 5 have the same configuration, but this is not restrictive. For example, it may include twisted pairs 3 using electric wires 31 with different outer diameters and conductor cross-sectional areas.

[0021] In each twisted pair 3, the twisting direction of the conductor 31a and the twisting direction of the twisted pair 3 are opposite to each other. This is because, for example, if the twisting directions of the conductor 31a and the twisted pair 3 are the same, the twisted pair 3 will be twisted in the direction in which the twist of the conductor 31a tightens, increasing the load on the metal strands included in the conductor 31a and potentially causing a disconnection when the cable 1 is bent. Note that the twisting direction of the conductor 31a is the direction in which the metal strands rotate from the other end side to the one end side when viewed from one end of the electric wire 31. Also, the twisting direction of the twisted pair 3 is the direction in which the electric wires 31 rotate from the other end side to the one end side when viewed from one end of the twisted pair 3.

[0022] Also, to suppress crosstalk, each twisted pair 3 constituting the assembly 5 is made to have a different twist pitch. The twist pitch of each twisted pair 3 may be different, for example, within the range of 10 mm to 20 mm. In this embodiment, for example, the twist pitches of the four twisted pairs 3 are set to 11 mm, 14 mm, 17 mm, and 19 mm respectively, so that the difference in the twist pitches of each twisted pair 3 is 2 mm or more. Note that the twist pitch of the conductor 31a is made the same as the twist pitch of the twisted pair 3 with the smallest twist pitch. Note that the twist pitch of the twisted pair 3 is the interval along the longitudinal direction of the twisted pair 3 at a location where any electric wire 31 has the same circumferential position in the circumferential direction of the twisted pair 3. Similarly, the twist pitch of the conductor 31a is the interval along the longitudinal direction of the conductor 31a at a location where any metal strand has the same circumferential position in the circumferential direction of the conductor 31a.

[0023] (Intervening member 4) The intermediate member 4 serves to prevent the electric wire 31 from being worn and broken due to friction between the twisted pairs 3 when the cable 1 is repeatedly bent, and to improve the bendability of the entire cable 1. The intermediate members 4 are respectively disposed between the twisted pairs 3 adjacent to each other in the circumferential direction. As the intermediate member 4, in order to perform the above functions, it is desirable to use a member having excellent cushioning properties. However, for example, when using a regenerated fiber such as spf (staple fiber) that is likely to absorb moisture, the transmission characteristics of the cable 1 may change depending on the moisture absorption state of the intermediate member 4, and sufficient transmission characteristics may not be obtained. Therefore, in the present embodiment, an intermediate member 4 made of a plurality of synthetic fibers is used.

[0024] As the synthetic fiber constituting the intermediate member 4, it is desirable to use a fiber that is less likely to absorb moisture than spf and has rich cushioning properties. For example, synthetic fibers such as polyamide-based and polyester-based fibers can be used. The intermediate member 4 is disposed around the twisted pair 3 so as to fill the gap between adjacent twisted pairs 3, between the twisted pair 3 and the tensile strength fiber 2, or between the twisted pair 3 and the wear suppression layer 6. The intermediate member 4 may be disposed in contact with the tensile strength fiber 2 disposed at the center of the cable. The fineness of the intermediate member 4 (the total fineness of the synthetic fibers disposed inside the aggregate 5) is preferably 3100 denier or more and 4400 denier or less, and more preferably 3900 denier or more and 4250 denier or less. The fact that the intermediate member 4 made of synthetic fiber has such a fineness and is disposed inside the aggregate 5 suppresses the electric wire 31 from being worn and broken due to friction between the twisted pairs 3 or friction between the wear suppression layer 6 and the twisted pair 3 when the cable 1 is repeatedly bent, and is effective in improving the mechanical properties of the entire cable 1 while having excellent transmission characteristics. The fineness of the intermediate member 4 disposed inside the aggregate 5 can be appropriately adjusted by changing the fineness of one synthetic fiber or the number of synthetic fibers. In the present embodiment, the fineness of the intermediate member 4 is 4200 denier. Further, in order for the intermediate member 4 to perform the above functions, the tensile strength of the synthetic fiber is preferably 49 N or more (more preferably 58 N or more), and the elongation is preferably 15% or more.

[0025] In this embodiment, nylon fiber, which is a polyamide-based synthetic fiber, is used as the synthetic fiber constituting the intervening member 4 that satisfies the above characteristics. The synthetic fiber (nylon fiber) constituting the intervening member 4 has a lower hygroscopicity than the tensile fiber (aramid fiber) constituting the tensile line 2. Also, the fineness of one synthetic fiber (nylon fiber) constituting the intervening member 4 is smaller than the fineness of one tensile fiber (aramid fiber). Specifically, the fineness of one synthetic fiber (nylon fiber) constituting the intervening member 4 is 0.1 times or more and 0.2 times or less the fineness of one tensile fiber (aramid fiber). The fineness of one synthetic fiber (nylon fiber) is, for example, 210 denier.

[0026] In this embodiment, the number of nylon fibers used in the entire cable 1 (disposed inside the aggregate 5) is set to 20. In particular, in this embodiment, intervening members 4 each composed of the same number of synthetic fibers are respectively disposed between each pair of adjacent twisted pairs 3 in the circumferential direction (each of the four locations). Thereby, when repeatedly bent, excellent transmission characteristics can be provided while improving the mechanical characteristics of the entire cable 1. The adjacent twisted pairs 3 do not necessarily have to be non-contact with each other by the intervening member 4 entering between the twisted pairs 3, and they may be in contact with each other at various positions in the longitudinal direction of the cable. That is, it is sufficient that the abrasion between the adjacent twisted pairs 3 in the circumferential direction is alleviated by the cushioning property of the intervening member 4.

[0027] (aggregate 5) The aggregate 5 is formed by twisting a plurality of (here, four) twisted pairs 3 and intervening members 4 around the tensile line 2. The twisting direction of the aggregate 5 is opposite to the twisting direction of the twisted pair 3. That is, the twisting direction of the aggregate 5 is the same as the twisting direction of the conductor 31a. Note that the twisting direction of the aggregate 5 is the direction in which the twisted pair 3 (and the intervening member 4) rotates from the other end side to the one end side of the aggregate 5 when viewed from one end of the aggregate 5. In this embodiment, the outer diameter of the aggregate 5 is about 4.4 mm.

[0028] (abrasion suppression layer 6) The wear suppression layer 6 is formed by spirally winding a tape member 61 made of fluororesin around the aggregate 5. For example, although it is also conceivable to provide the wear suppression layer 6 by extrusion molding, in this case, since the wear suppression layer 6 becomes cylindrical, it becomes very hard and difficult to bend, and the flexibility of the cable 1 is reduced. In the present embodiment, while suppressing a decrease in the flexibility of the cable 1, when the cable 1 is repeatedly bent, the insulator 31b is worn due to side pressure wear occurring between the shield layer 7 composed of a plurality of metal strands and the insulator 31b composed of an insulating resin material. In order to suppress this, the wear suppression layer 6 is formed by spirally winding a tape member 61 made of fluororesin around the insulator 31b.

[0029] The winding direction of the tape member 61 is preferably the same as the twisting direction of the aggregate 5. Thereby, the tape member 61 easily enters the concave portion (valley portion) of the aggregate 5, that is, the valley portion between the pair of twisted strands 3 adjacent in the circumferential direction, and the contact area between the tape member 61 and the pair of twisted strands 3 (electric wire 31) is increased, and it becomes possible to further suppress the wear of the electric wire 31 by the shield layer 7.

[0030] The tape member 61 is wound spirally around the outer periphery of the aggregate 5 by overlapping a part of the width direction of the fluororesin tape. At this time, the tape member 61 is wound so that the surface of the pair of twisted strands 3 (insulator 31b of the electric wire 31) is not exposed from the overlapping portion of the tape member 61 when the cable 1 is bent, swung, or subjected to squeezing motion. Further, the overlapping portions of the tape member 61 are not adhered to each other, and when the cable 1 is bent, swung, or subjected to squeezing motion, the overlapping tape members 61 can move so as to slide in the longitudinal direction of the cable 1 relative to each other.

[0031] Further, it is desirable that the tape member 61 made of a fluororesin has a non-adhesive surface with respect to each of the insulator 31b of the electric wire 31 constituting the twisted pair wire 3 and the shield layer 7. Here, the "tape member 61 made of a fluororesin" means a tape member 61 uniformly formed of a fluororesin. Further, in order to obtain the above-described actions and effects, it is desirable that the overlapping portion of the tape member 61 is wound so as to be 0.3 times or more and 0.5 times or less the width of the tape member 61 (for example, 15 mm to 35 mm).

[0032] When the cable 1 is repeatedly bent (especially when a heavy load is applied), the cable 1 is subjected to lateral pressure. However, in the cable 1 according to the present embodiment, by providing the above-described wear suppression layer 6 between each twisted pair wire 3 and the shield layer 7, it is possible to suppress the insulator 31b of the electric wire 31 constituting the twisted pair wire 3 and the shield layer 7 from rubbing against each other due to lateral pressure and the insulator 31b from wearing out. That is, by providing the wear suppression layer 6, the surface of the wear suppression layer 6 that contacts the insulator 31b of each electric wire 31 and the surface of the wear suppression layer 6 that contacts the shield layer 7 are less likely to wear due to lateral pressure. Therefore, the durability when the cable 1 is repeatedly bent, particularly the durability when a heavy load such as squeezing is applied (hereinafter simply referred to as durability against squeezing) can be improved.

[0033] When the cable 1 is bent, swung, or given a squeezing-like movement, it is desirable that the wear suppression layer 6 can move so that the shield layer 7 slides with respect to the wear suppression layer 6. That is, it is desirable that the surface of the wear suppression layer 6 has good slipperiness (the friction coefficient is lower than the friction coefficient of the surface of the insulator 31b). Examples of the fluororesin used for the tape member 61 include ETFE (tetrafluoroethylene-ethylene copolymer) and PTFE (polytetrafluoroethylene). In the present embodiment, a tape member 61 made of PTFE having good surface slipperiness and a low dielectric constant is used.

[0034] The thickness of the tape member 61 is preferably 25 μm or more and 150 μm or less. When the thickness of the tape member 61 is 25 μm or more, it becomes difficult to break due to repeated abrasion. When the thickness of the tape member 61 is 150 μm or less, a wear suppression layer 6 having a hardness that can hardly reduce the flexibility of the cable 1 can be obtained. In the present embodiment, a tape member 61 made of a PTFE tape with a thickness of about 100 μm is used. The tape member 61 made of a PTFE tape is less likely to absorb moisture than the intervening layer 4 made of synthetic fiber and has a low dielectric constant ε of 2.1, so it is effective for achieving both suppression of wear and breakage of the electric wire 31 and excellent transmission characteristics.

[0035] In the present embodiment, as shown in FIGS. 2(a) and 2(b), a (single-layer) tape member 61 having a single layer of fluororesin layer 611 is used. However, the present invention is not limited to this. As long as the surface 61a facing the aggregate 5 and the surface 61b facing the shield layer 7 of the tape member 61 are made of fluororesin. For example, as shown in FIGS. 2(c) and 2(d), the tape member 61 may have a multilayer structure of two or more layers. FIG. 2(c) shows an example in which the surfaces 61a and 61b are both made of fluororesin by laminating the fluororesin layer 611 in multiple layers (two layers in the illustrated example). The tape member 61 in FIG. 2(c) can be formed, for example, by bonding films made of fluororesin. Further, FIG. 2(d) shows an example in which the surfaces 61a and 61b are both made of fluororesin by providing fluororesin layers 611 on both surfaces of the base material 612. The tape member 61 in FIG. 2(d) can be formed, for example, by applying and curing fluororesin on the entire surfaces of both sides of the base material 612 to form the fluororesin layer 611, or by bonding films made of fluororesin on the entire surfaces of both sides of the base material 612 and fusing the films and the base material 612.

[0036] (Shield layer 7) The shield layer 7 is for shielding external noise. In order to ensure the flexibility of the cable 1 that covers the outer periphery of the wear suppression layer 6, the shield layer 7 is composed of a braided shield in which metal strands are woven. In the present embodiment, the shield layer 7 is configured by laminating a plurality of layers of braided shields. Here, a case where the shield layer 7 is configured by laminating two layers of braided shields will be described, but the shield layer 7 may be configured by laminating three or more layers of braided shields. Hereinafter, the braided shield provided on the inner side in the radial direction is referred to as the inner braided shield 71, and the braided shield provided on the outer side in the radial direction is referred to as the outer braided shield 72.

[0037] In the cable 1 according to the present embodiment, an air layer (not shown) may be formed between the shield layer 7 (inner braided shield 71) and the wear suppression layer 6 in a part in the circumferential direction. To form the air layer, the inner diameter of the inner braided shield 71 may be made larger than the outer diameter of the wear suppression layer 6. In the present embodiment, when forming the inner braided shield 71, for example, a rod-shaped spacer incorporated in a braiding forming device is arranged along the cable longitudinal direction on the outer circumference of the wear suppression layer 6, and metal strands are braided on the spacer to form the inner braided shield 71. By sequentially feeding out the formed inner braided shield 71 from the braiding forming device so as to be detached from the spacer, an air layer can be formed. Note that the shape of the spacer is not limited to a rod shape. The size of the air layer is such that the maximum distance from the surface of the wear suppression layer 6 to the inner surface of the shield layer 7 (the surface facing the surface of the wear suppression layer 6) is in the range of 5 μm or more and 30 μm or less, and it is preferable that the shield layer 7 floats from the surface of the wear suppression layer 6 toward the sheath 8 side. Here, the maximum distance is obtained by measuring the maximum value of the linear distance from the surface of the wear suppression layer 6 to the inner surface of the shield layer 7 when the cross section (a cross section perpendicular to the cable longitudinal direction) of the cut part is observed using an optical microscope or an electron microscope after cutting the cable 1 at a predetermined position. By forming an air layer between the shield layer 7 (inner braided shield 71) and the wear suppression layer 6, the clamping by the shield layer 7 is suppressed, and when the cable 1 is bent, swung, or squeezed, the shield layer 7 (inner braided shield 71) and the wear suppression layer 6 can easily move relative to each other in the longitudinal direction of the cable 1, making it possible to improve the bending resistance, twist resistance, and durability against squeezing.

[0038] The outer braided shield 72 is formed by braiding metal strands on the outer circumference of the inner braided shield 71 in the same manner as the manufacturing method of a normal braided shield. Therefore, no air layer is formed between the inner braided shield 71 and the outer braided shield 72. This is because if an air layer is formed between the inner braided shield 71 and the outer braided shield 72, the contact resistance within the shield layer 7 will increase, possibly causing characteristic degradation.

[0039] As the metal strands used for the double braided shields 71 and 72, in order to sufficiently obtain flexural resistance and twist resistance, a semi-hard copper alloy wire with a tensile strength of 350 MPa or more and an elongation of 7% or more and 15% or less is used. By setting the elongation of the metal strand to 7% or more, it becomes possible to withstand large twists such as ±180°. By setting the elongation to 15% or less, it is possible to suppress a decrease in the mechanical strength of the metal strand. In the present embodiment, as the metal strand used for the double braided shields 71 and 72, a tinned copper alloy wire with a strand diameter of 0.08 mm is used. Also, the density of the double braided shields 71 and 72 is set to about 85%. Note that the metal strands used for the double braided shields 71 and 72 may be the same or different even if the strand diameters are the same.

[0040] Furthermore, in the present embodiment, metal strands coated with a lubricant can be used for the double braided shields 71 and 72. As the lubricant, for example, liquid paraffin can be used. Thereby, the shield layer 7 and the wear suppression layer 6 become more slippery, and it becomes possible to further improve flexural resistance, twist resistance, and durability against squeezing.

[0041] By the way, if the braiding angle of the inner braided shield 71 is large, there is a risk that the rubbing against the wear suppression layer 6 will become intense. Also, if the braiding angle of the outer braided shield 72, which is easily affected by bending, is small, there is a risk that the metal strands will easily break and the flexural resistance will decrease. Furthermore, if the braiding angles of the double braided shields 71 and 72 are the same, there is a risk that the wear between the double braided shields 71 and 72 will increase. Therefore, the braiding angle of the inner braided shield 71 is preferably smaller than the braiding angle of the outer braided shield 72. When the shield layer 7 has three or more braided shields, the braiding angle of the braided shield provided most inward in the radial direction is preferably smaller than the braiding angle of the braided shield provided outward of the braided shield. Note that the braiding angle is the angle (absolute value) formed between the longitudinal direction of the metal strand and the longitudinal direction of the cable 1.

[0042] (Sheath 8) The sheath 8 is formed so as to cover the periphery of the shield layer 7 (outer braided shield 72). As the sheath 8, for example, those made of PVC (polyvinyl chloride) or urethane can be used. It is desirable that the sheath 8 be formed by tube extrusion so that the shield layer 7 can move within the sheath 8. In this embodiment, a sheath 8 made of PVC with a thickness of 0.8 mm is provided. The outer diameter of the sheath 8, that is, the outer diameter of the cable 1, is about 7.0 mm.

[0043] (Characteristic Test) The cable 1 shown in FIG. 1 was manufactured, and the mechanical characteristics and transmission characteristics of the manufactured cable 1 were tested. The test results are summarized in Table 1. Note that the transmission characteristics in Table 1 show the measurement results for the cable 1 after 200,000 flexing tests. Also, the characteristic impedance shows the value measured by the TDR (Time Domain Reflectometry) method. The attenuation is measured at a cable length of 4.9 m and shown as the value converted to a cable length of 40 m. In Table 1, the standard values of the mechanical characteristics and transmission characteristics are also shown, and the standard values of the transmission characteristics are the standard values for Category 5e LAN cables.

[0044] [Table 1]

[0045] In the bending test, as shown in FIG. 3(a), the cable 1 was fixed so that the movement of the core wire of the cable 1 did not occur, and a left-right 90-degree bending test was repeated in which the cable 1 was bent 90 degrees to the left and right. Taking the cycle of the arrows a to d shown in FIG. 3(a) as one time, the bending was repeated at a speed of 30 times per minute. All the electric wires 31 included in the cable 1 were connected in series, and a voltage of several volts was applied by a constant voltage source. The number of times when the conductor resistance value increased by 20% with respect to the initial value (the conductor resistance value in the state before repeating the bending) was actually measured, and it was determined that the cable was disconnected when the obtained actual measurement value (number of times) was reached. Also, in the bending test, the bending radius was 19 mm and the load W was 0.5 kgf (4.9 N).

[0046] In the twisting test, as shown in Fig. 3(b), the cable 1 was fixed so that the core of the cable 1 did not move, and a ±180° twisting test was performed in which the cable 1 was repeatedly twisted by ±180°. Taking the cycles of the arrows a to d shown in Fig. 3(b) as one time, the twisting was repeated at a speed of 30 times per minute. Regarding the determination of wire breakage, it was the same as in the bending test. That is, all the wires 31 included in the cable 1 were connected in series, a voltage of several volts was applied by a constant voltage source, and the number of times when the conductor resistance value increased by 20% compared to the initial value (the conductor resistance value in the state before repeating the twisting) was actually measured, and it was determined that the wire broke at the obtained measured value (number of times). Also, in the twisting test, the twisting length was 500 mm and the load W was 0.5 kgf (4.9 N).

[0047] In the squeezing test, as shown in Fig. 3(c), using the slide part 9 having two pulleys 91, with the cable 1 being deflected by 180° in each pulley 91 and the cable 1 arranged in a crank shape, the slide part 9 was repeatedly translated left and right with a constant stroke. Taking the cycles (one round trip) of the arrows a and b shown in Fig. 3(c) as one time, the slide part 9 was reciprocated at a speed of 10 times per minute. Regarding the determination of wire breakage, it was the same as in the bending test. That is, all the wires 31 included in the cable 1 were connected in series, a voltage of several volts was applied by a constant voltage source, and the number of times when the conductor resistance value increased by 20% compared to the initial value (the conductor resistance value in the state before repeating the sliding of the slide part 9) was actually measured, and it was determined that the wire broke at the obtained measured value (number of times). Also, in the squeezing test, the diameter of the pulley 91 was 80 mm, and the loads at both ends of the cable 1 were each 0.5 kgf (4.9 N).

[0048] In the U-shaped slide test, as shown in Fig. 3(d), the cable 1 was arranged in a U-shape between the fixed plate 95 and the movable plate 96 which were arranged opposite to each other. One end of the cable 1 was fixed to the fixed plate 95 and the other end was fixed to the movable plate 96. The movable plate 96 was repeatedly translated in parallel with a certain stroke. The cycle (one round trip) of the arrows a and b shown in Fig. 3(d) was regarded as one time, and the movable plate 96 was reciprocated at a speed of 60 times per minute. Regarding the judgment of disconnection, it was the same as the bending test. That is, all the electric wires 31 included in the cable 1 were connected in series, and a voltage of several volts was applied by a constant voltage source. The number of times when the conductor resistance value increased by 20% compared with the initial value (the conductor resistance value in the state before repeating the parallel movement of the movable plate 96) was actually measured, and it was judged that the cable was disconnected when the obtained actual measurement value (number of times) was reached. Also, in the U-shaped slide test, the moving stroke was 300 mm and the bending radius of the cable 1 was 60 mm.

[0049] As shown in Table 1, in the cable 1, in the bending test, the twisting test, the ironing test, and the U-shaped slide test, actual measurement values above the standard values were obtained in all cases, and it was confirmed that excellent bend resistance, twist resistance, resistance to ironing, and resistance to U-shaped slide were obtained. Also, regarding the transmission characteristics, it was confirmed that the standard value of Category 5e was satisfied and long-distance transmission of 40 m was possible.

[0050] (Actions and Effects of the Embodiment) As described above, in the cable 1 according to the present embodiment, a tensile strength wire 2 made of a tensile strength fiber disposed at the center of the cable, a plurality of pair-twisted wires 3 formed by twisting a pair of electric wires 31 and twisted around the tensile strength wire 2, an intervening member 4 made of a plurality of synthetic fibers disposed around the pair-twisted wires 3, and a wear suppression layer 6 formed by spirally winding a tape member 61 around an aggregate 5 formed by twisting a plurality of pair-twisted wires 3 and the intervening member 4 around the tensile strength wire 2, a shield layer 7 made of a braided shield covering the outer periphery of the wear suppression layer 6, and a sheath 8 covering the periphery of the shield layer 7. The wear suppression layer 6 has a surface 61a facing the aggregate 5 of the tape member 61 and a surface 61b facing the shield layer 7 formed of a fluororesin, and the tape member 61 is non-adhesively overlapped so that a part in the width direction of the tape member 61 overlaps.

[0051] By providing the tensile strength wire 2 at the center of the cable, the durability against the tension received by the cable 1 due to repeated bending can be enhanced. Also, by disposing the intervening member 4 made of a plurality of synthetic fibers between at least the pair-twisted wires 3 adjacent in the circumferential direction, wear and breakage of the pair-twisted wires 3 due to rubbing can be suppressed by the cushioning property of the intervening member 4. Further, by using a synthetic fiber with low hygroscopicity for the intervening member 4, deterioration of transmission characteristics due to moisture absorption can be suppressed, and the cable 1 can maintain transmission characteristics regardless of the usage environment, realizing a cable 1 having excellent transmission characteristics enabling large-capacity data communication. Furthermore, by providing the wear suppression layer 6 between the aggregate 5 and the shield layer 7, disconnection of the electric wire 31 due to rubbing against the shield layer 7 can be suppressed. Therefore, a cable 1 in which problems such as disconnection hardly occur when repeatedly bent can be realized, and a cable 1 with high durability against bending, swinging, and squeezing can be realized.

[0052] (Summary of the embodiment) Next, the technical idea grasped from the above-described embodiment will be described by referring to the reference numerals and the like in the embodiment. However, each reference numeral and the like in the following description are not limited to the members specifically shown in the embodiment for the components in the claims.

[0053] [1] A cable (1) comprising: a tensile strength wire (2) made of tensile strength fibers disposed at the center of the cable; a plurality of pair-twisted wires (3) formed by twisting a pair of electric wires (31) and twisted around the tensile strength wire (2); an intervening layer (4) made of a plurality of synthetic fibers disposed around the pair-twisted wires (3); a wear suppression layer (6) formed by spirally winding a tape member (61) around an aggregate (5) formed by twisting the plurality of pair-twisted wires (3) and the intervening layer (4) around the tensile strength wire (2); a shield layer (7) formed of a braided shield covering the outer periphery of the wear suppression layer (6); and a sheath (8) covering the periphery of the shield layer (7). The wear suppression layer (6) has a surface (61a) facing the aggregate (5) of the tape member (61) and a surface (61b) facing the shield layer (7) formed of a fluororesin, and the tape member (61) is non-adhesively wound so that a part in the width direction of the tape member (61) overlaps.

[0054] [2] The cable (1) according to [1], wherein the intervening layer (4) has a fineness of 3100 denier or more and 4400 denier or less.

[0055] [3] The cable (1) according to [1] or [2], wherein the tensile strength fibers constituting the tensile strength wire (2) have a larger fineness than the synthetic fibers constituting the intervening layer (4).

[0056] [4] The cable (1) according to any one of [1] to [3], wherein the synthetic fibers constituting the intervening layer (4) have a tensile strength of 49 N or more and an elongation of 15% or more.

[0057] [5] The cable (1) according to any one of [1] to [4], wherein the synthetic fibers constituting the intervening layer (4) are made of nylon fibers.

[0058] [6] The cable (1) according to any one of [1] to [5], wherein the tape member (61) constituting the wear suppression layer (6) is made of polytetrafluoroethylene.

[0059] [7] The wear suppression layer (6) is the cable (1) according to any one of [1] to [6], wherein the winding direction of the tape member (61) is the same as the twisting direction of the aggregate (5).

[0060] [8] The wear suppression layer (6) is the cable (1) according to any one of [1] to [7], wherein the friction coefficient of the surface of the tape member (61) is lower than the friction coefficient of the surface of the insulator (31b) of the electric wire (31).

[0061] [9] The shield layer (7) is the cable (1) according to any one of [1] to [8], which is formed by laminating a plurality of layers of braided shields.

[0062]

[10] The shield layer (7) is the cable (1) according to any one of [1] to [9], which consists of a braided shield in which a copper alloy wire having a tensile strength of 350 MPa or more and an elongation of 7% or more and 15% or less is woven.

[0063] As described above, the embodiments of the present invention have been described. However, the above-described embodiments do not limit the invention according to the claims. It should also be noted that not all combinations of the features described in the embodiments are essential for the means for solving the problems of the invention. Further, the present invention can be appropriately modified and implemented without departing from the spirit thereof.

Description of Reference Numerals

[0064] 1... Cable 2... Tensile strength wire 3... Twisted pair wire 31... Electric wire 31a... Conductor 31b... Insulator 4... Intervening 5... Aggregate 6... Wear suppression layer 61... Tape member 61a, 61b... Surfaces 611... Fluororesin layer 612... Base material 7... Shield layer 71... Inner braided shield 72…Outer braided shield 8…Sheath

Claims

1. A plurality of pairs of twisted wires formed by twisting a pair of electric wires having an insulator around a conductor, An intervening member made of a plurality of synthetic fibers disposed around the plurality of pairs of twisted wires, A tape member spirally wound around an aggregate formed by twisting the plurality of pairs of twisted wires and the intervening member, A shield layer composed of a braided shield covering the outer periphery of the tape member, A sheath covering the periphery of the shield layer, and comprising, The surface friction coefficient of the tape member is lower than the surface friction coefficient of the insulator, The shield layer has an inner braided shield provided radially inward and an outer braided shield provided radially outward, The braiding angle of the inner braided shield is smaller than the braiding angle of the outer braided shield, The synthetic fiber has a tensile strength of 49 N or more and an elongation of 15% or more, Cable.

2. The synthetic fiber is made of nylon fiber, The cable according to claim 1.

3. The insulator is made of polypropylene, The cable according to claim 1 or 2.

4. The tape member is wound in an overlapping manner such that a part in the width direction overlaps, The cable according to any one of claims 1 to 3.

5. The twisting direction of the aggregate is opposite to the twisting direction of the plurality of pairs of twisted wires, The cable according to any one of claims 1 to 4.

6. In a part in the circumferential direction, an air layer is formed between the inner braided shield and the tape member, The cable according to any one of claims 1 to 5.

7. The insulator has a non-solid extrusion layer provided on the outer periphery of the conductor by tube extrusion, a foam layer provided non-adhesively on the outer periphery of the non-solid extrusion layer, and a non-foam layer provided adhesively on the outer periphery of the foam layer, The cable according to any one of claims 1 to 6.

8. The foam layer is made of a resin material having a lower melting point than the resin material of the non-solid extrusion layer, The cable according to claim 7.

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