Composite cable

Abstract

To improve stability of a position of a cable core relative to a sheath of a composite cable.SOLUTION: A composite cable 1 comprises a plurality of power lines 3 each having an insulating layer on the outer periphery of a conductor 31, and at least a pair of twisted signal lines, each pair comprising two signal lines 2 each having an insulating layer on the outer periphery of a conductor 21, which are twisted together, and an outer sheath 4 formed on the outer periphery of a cable core 20 in which all of the power lines and all of the pairs of twisted signal lines are twisted together, wherein when the outer sheath covers the cable core over a length of 50 mm, the pull-out force of the cable core from the outer sheath is 60 N or more and 90 N or less.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Composite cables are used in a variety of products, including industrial machinery, industrial robots, and vehicles (automobiles, trains, etc.). Such composite cables are generally formed by twisting together a plurality of electric wires with different outer diameters to form a cable core, and then covering the cable core with a sheath (see, for example, Patent Document 1). Also, a composite cable is used in which the cable cores are bundled with a pressure winding and covered with a sheath (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2020 / 196048 [Patent Document 2] International Publication No. 2020 / 111162 Summary of the Invention [Problem to be solved by the invention]

[0004] Depending on the application, composite cables are required to have, for example, abrasion resistance, flexibility, heat resistance, low temperature resistance, and bending resistance. However, the requirements for a composite cable are not limited to the above. For example, depending on the application of the composite cable, mechanical movement, vibration, etc. may cause fluctuations in the relative position between the connection destinations at one end and the other end of the composite cable. In such cases, the composite cable is required to have stable positioning of the cable core relative to the sheath, but the composite cables of Patent Documents 1 and 2 do not take into consideration the stability of positioning of the cable core relative to the sheath.

[0005] The present invention has been made in view of the above problems, and has as its object to improve the stability of the position of a cable core relative to a sheath of a composite cable. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention provides: a plurality of power lines each having an insulating layer around a conductor; at least one pair of twisted signal wires, each of which is formed by twisting together two signal wires having an insulating layer around the outer periphery of a conductor; a composite cable including a cable core formed by twisting all of the power supply wires and all of the twisted pair signal wires together, and an outer sheath formed around the outer periphery of the cable core, The cable is characterized in that the force required to pull out the cable core from the outer sheath is 60 [N] or more and 90 [N] or less when the outer sheath covers the cable core within a length of 50 [mm]. [Effects of the Invention]

[0007] According to the present invention, it is possible to improve the stability of the position of the cable core relative to the sheath. [Brief explanation of the drawings]

[0008] [Figure 1] This is a diagram showing the state in which the signal line of the composite cable is connected to the ABS sensor and the ABS control device, and the power line is connected to the EPB control device and the actuator. [Figure 2] 1 is a cross-sectional view showing an example of the configuration of a composite cable according to an embodiment of the present invention, showing a four-core configuration. [Figure 3] 1 is a cross-sectional view showing an example of the configuration of a composite cable according to an embodiment of the present invention, showing a case of six cores. [Figure 4] 10 is a diagram showing that the conductor of the power supply line or signal line is made up of a plurality of strands twisted together. FIG. [Figure 5]Figure 5(a) shows a state in which four signal wires and power wires are twisted together within a composite cable, and Figure 5(b) shows a state in which six signal wires and power wires are twisted together within a composite cable. [Figure 6] 1 is a cross-sectional view showing an example of the configuration of a composite cable, in which the cable core is configured with four cores and a pressure winding is provided. [Figure 7] 1 is a cross-sectional view showing an example of the configuration of a composite cable, in which the cable core is composed of six cores and a pressure winding is provided. [Figure 8] 1 is a table showing the results of evaluation of "stability of cable core" and "flexibility" for Examples and Comparative Examples. [Figure 9] FIG. 1 is an explanatory diagram showing a method for measuring the pull-out force of a cable core from an outer sheath. [Figure 10] FIG. 10 is an explanatory diagram showing a method for measuring the stability of a cable core. [Figure 11] FIG. 10 is an explanatory diagram showing a method for measuring the flexibility of a composite cable. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Outline of composite cable] Hereinafter, a composite cable according to the present invention will be described with reference to the drawings. However, although the embodiments described below are subject to various limitations that are technically preferable for implementing the present invention, the scope of the present invention is not limited to the following embodiments or illustrated examples. In the following description, "numeric value A to numerical value B" refers to a range of "numerical value A or more and numerical value B or less."

[0010] The composite cable 1 comprises a cable core 20 made up of a plurality of electric wires, namely, signal wires 2 and power wires 3, each having a resin layer 22, 32 as an insulating layer around the periphery of a conductor 21, 31, and an outer sheath 4 covering the periphery of the cable core 20.

[0011] The composite cable 1 can be used as a cable for electronic control of various machines or devices, such as industrial machines, industrial robots, vehicles, and the like. For example, as shown in FIG. 1, the multiple signal lines 2 of the composite cable 1 include a signal line for transmitting a signal from a sensor 11 of an antilock braking system to a control device 12, and the multiple power supply lines 3 include a power supply line for supplying power from a control device 13 of an electric parking brake to an actuator 14, but the use of the composite cable 1 is not limited to this case.

[0012] 2 and 3 are cross-sectional views showing configuration examples of the composite cable 1 according to this embodiment. Fig. 2 shows a four-core cable with two signal wires 2 and two power wires 3, where two signal wires 2 are twisted together to form one set of twisted-pair signal wires. Fig. 3 shows a six-core cable with four signal wires 2 and two power wires 3, where two sets of four signal wires 2 are twisted together in pairs to form two sets of twisted-pair signal wires. Note that the number of sets of twisted-pair signal wires in the signal wires 2 and the number of power wires 3 are merely examples and are not limited to the above examples. In this embodiment, the composite cable 1 includes multiple sets of twisted-pair signal wires and multiple power wires 3, and each of the signal wires 2 and power wires 3 has an insulating resin layer 22, 32 around the outer periphery of the conductor 21, 31. The multiple signal wires 2 and multiple power wires 3 are collectively covered with an outer sheath 4. The outer sheath 4 may be made up of multiple layers.

[0013] The outer diameter of the signal line 2 is not particularly limited, but is exemplified as 0.5 to 2.5 mm in terms of strength and flexibility. The outer diameter of the power line 3 is not particularly limited, but is exemplified as 1.5 to 4.0 mm in terms of strength and flexibility.

[0014] As shown in FIG. 4, the conductors 21 and 31 of the signal line 2 and the power line 3 are conductors formed by twisting together a plurality of strands 21a and 31a. The wires 21a and 31a may be made of, for example, soft copper, copper alloy, tin alloy, or aluminum alloy, and may be bare wires or may be plated with tin or the like.

[0015] The resin layers 22 and 32 of the signal line 2 and the power line 3 cover the conductors 21 and 31 . The material constituting the resin layer 22 can be, for example, polyethylene (PE), flame-retardant cross-linked polyethylene (flame-retardant XLPE), cross-linked polyethylene (XLPE), tetrafluoroethylene-ethylene copolymer (ETFE), ethylene vinyl acetate (EVA), or other thermoplastic elastomers (TPE). Furthermore, the material constituting the resin layer 32 can be, for example, polyethylene (PE), flame-retardant cross-linked polyethylene (flame-retardant XLPE), cross-linked polyethylene (XLPE), tetrafluoroethylene-ethylene copolymer (ETFE), polypropylene (PP), ethylene vinyl acetate (EVA), or other thermoplastic elastomers (TPE).

[0016] 2 and 3, the dashed circles including pairs of signal wires 2 indicate that the signal wires 2 are twisted pair signal wires in which two signal wires 2 are twisted together. A twisted pair signal wire has higher flexibility than signal wires 2 that are not twisted together.

[0017] 5(a) and 5(b), the composite cable 1 has the signal wires 2 and power wires 3 twisted together inside the outer sheath 4, which are further twisted together overall to form a cable core 20. The twist pitch of the cable core 20 shown here is 20 to 75 mm. This allows the composite cable 1 to stretch as a whole, improving overall flexibility and repetitive bending resistance. FIG. 5(a) shows the case where the composite cable 1 has four cores (see FIG. 2), and FIG. 5(b) shows the case where the composite cable 1 has six cores (see FIG. 3).

[0018] [Outer sheath] Examples of materials that can be used to form the outer sheath 4 include ester-based thermoplastic polyurethane elastomer (TPU), ether-based polyurethane, ethylene-vinyl acetate copolymer (EVA), and low-density polyethylene (LLDPE).The outer sheath 4 may be made of any of the above materials that have been crosslinked, or may contain flame retardants or antioxidants, such as metal hydrates, bromine-based flame retardants, and antimony trioxide. The cable core 20, in which the twisted pair signal wires and the power wires 3 are twisted together, was extruded using a general-purpose extruder to cover the outer periphery of the cable core 20 with the outer sheath 4.

[0019] [Pressure wrapping] 6 and 7, the composite cable 1 may have a configuration in which the cable core 20 has a pressure wrap 5 around the outer periphery of the twisted pair signal wires and the power wires 3. Fig. 6 shows an example in which the pressure wrap 5 is provided around the twisted pair of one twisted pair signal wires and two power wires 3 (the same configuration as Fig. 2), and Fig. 7 shows an example in which the pressure wrap 5 is provided around the twisted pair of two twisted pair signal wires and two power wires 3 (the same configuration as Fig. 3). The pressure wrap 5 is made of a tape made of paper, nonwoven fabric, or resin such as polyester, with a width of 15 to 25 mm, and is spirally wound with a winding pitch of 20 to 50 mm around the twisted pair of signal wires and power wires 3. The tape used for the pressure wrap 5 is 0.03 to 0.05 mm thick.

[0020] [Pull-out force of cable core from outer sheath] The composite cable 1 is characterized in that when the portion of the outer sheath 4 covering the cable core 20 is cut out within a length of 50 mm and the cable core 20 is pulled out from the outer sheath 4, the pulling force is in the range of 60 N or more and 90 N or less. When the cable core 20 of the composite cable 1 has the pressure windings 5, the pull-out force of the cable core 20 having the pressure windings 5 ​​from the outer sheath 4 falls within the above range. The pull-out force of the cable core 20 from the outer sheath 4 depends on the resin pressure during extrusion molding of the material of the outer sheath 4. If the resin pressure is high, the outer sheath 4 will have a stronger adhesion to the outer surface of the cable core 20 and will penetrate into unevenness and gaps, thereby increasing the pull-out force. Therefore, the composite cable 1 is adjusted by appropriately adjusting the resin pressure during extrusion molding of the material of the outer sheath 4 so that the pull-out force of the cable core 20 from the outer sheath 4 is in the range of 60 [N] or more and 90 [N] or less.

[0021] [Example] The present invention will be described in detail below based on examples, but is not limited to these. Fig. 8 is a table showing the results of evaluation of "cable core stability" and "flexibility" for Examples 1 to 8 and Comparative Examples 1 and 2.

[0022] All of Examples 1 to 6 and Comparative Examples 1 and 2 are four-core composite cables in which a cable core 20 consisting of a set of twisted-pair signal wires formed by twisting together the two signal wires 2 described above and two power wires 3 is covered with an outer sheath 4. In addition, both Examples 7 and 8 are six-core composite cables in which a cable core 20 consisting of two sets of twisted-pair signal wires formed by twisting together the two signal wires 2 described above and two power wires 3 is covered with an outer sheath 4. Furthermore, the outer diameter of the signal line 2 is 1.4 mm, and the resin layer 22 is made of polyethylene (PE) to which magnesium hydroxide has been added. The power line 3 has an outer diameter of 2.8 mm, and the resin layer 32 is made of polyethylene (PE) with magnesium hydroxide added. The outer sheath 4 is made of flame-retardant cross-linked polyethylene and covers the outer periphery of the cable core 20 by extrusion molding using a general-purpose extruder. The outer diameter of each four-core composite cable is 8.3 mm. The outer diameter of each of the six-core composite cables is 9.1 mm.

[0023] Moreover, Examples 2, 5, 7, and 8 do not have a pressure wrap 5, while Examples 1, 3, 4, and 6 and Comparative Examples 1 and 2 all have a pressure wrap 5. Each of the pressure windings 5 ​​is made of polyester tape 20 mm wide and 0.03 mm thick, and is spirally wound with a winding pitch of 30 mm around the outer periphery of the twisted pair of signal wires and power wires 3.

[0024] In addition, in all of Examples 1 to 8, the pull-out force of the cable core 20 from the outer sheath 4 is in the range of 60 [N] or more and 90 [N] or less, while in all of Comparative Examples 1 and 2, the pull-out force is outside the above range. Specifically, the pull-out force is 60 [N] in Examples 1, 2, and 7, 70 [N] in Example 3, 80 [N] in Example 4, 90 [N] in Examples 5, 6, and 8, 50 [N] in Comparative Example 1, and 100 [N] in Comparative Example 2.

[0025] As described above, the force required to pull out the cable core 20 from the outer sheath 4 depends on the resin pressure during extrusion molding of the flame-retardant cross-linked polyethylene that is the material of the outer sheath 4 . Therefore, several types of composite cables were prepared, each manufactured by extrusion molding the outer sheath 4 at a plurality of resin pressures around a cable core 20 consisting of the above-mentioned signal wire 2 and power wire 3 and the cable core 20 with the above-mentioned signal wire 2 and power wire 3 subjected to pressure wrapping 5. The pull-out force was measured using the method described below, and the composite cables for which the measured pull-out force gave corresponding numerical values ​​were designated as Examples 1 to 8 and Comparative Examples 1 and 2.

[0026] Here, we will explain how to measure the pull-out force of the cable core 20 from the outer sheath 4. Figure 9 is an explanatory diagram showing the measurement method. As described above, several types of composite cables were prepared by extrusion molding the outer sheath 4 at various resin pressures for cable cores 20 without pressure wraps 5 and cable cores 20 with pressure wraps 5, and test pieces were prepared by cutting each of them to a cable length of 100 mm. Then, for each test piece, a slit is made in the outer sheath 4 at a position 50 mm from one end and the outer sheath 4 is stripped off to expose a 50 mm length of the cable core 20. Furthermore, the remaining 50 mm length of the outer sheath 4 is fixed with a fixture H so as not to move toward the exposed cable core 20. Then, as shown by the arrow, the cable core 20 is pulled out from the outer sheath 4 at a speed of 200 mm / min. At this time, the pull-out force of the cable core 20 is measured using a load cell, and the maximum pull-out force until the cable core 20 is pulled out from the outer sheath 4 is defined as the pull-out force of the core from the cable covering for the test piece.

[0027] "Cable core stability" The composite cables of Examples 1 to 8 and Comparative Examples 1 and 2 were evaluated for stability of the cable core 20. FIG. 10 is an explanatory diagram showing a method for measuring the stability of a cable core. For each of the composite cables of Examples 1 to 8 and Comparative Examples 1 and 2, a test piece was prepared by cutting the cable into a length of 100 mm. Then, for each test piece, a slit is made in the outer sheath 4 at a position 50 mm from one end, and the outer sheath 4 is stripped off to expose the cable core 20 over a length of 50 mm. 10, the exposed cable core 20 was fixed with a fixture H and held by a pair of mandrels M at a position 20 mm from the end of the remaining outer sheath 4 on the exposed cable core 20 side. Each mandrel M was cylindrical with an outer diameter of 10 mm, and its central axis was oriented in a direction perpendicular to the composite cable test specimen.

[0028] At the boundary position G between the cable core 20 and the outer sheath 4 in the test piece held by the fixture H and each mandrel M, a mark is made in advance on the outer peripheral surface of the cable core 20. The test piece was then bent over a 90° range so as to alternately wrap around the outer circumference of both mandrels M. The bending test was performed at a speed of 60 times / min, with each 90° bend so as to wrap around one of the mandrels M being counted as one bend. After a total of 10 alternating bends, the test piece was returned to a straight state, and if the end of the outer sheath 4 on the exposed cable core 20 side was located within a range of less than 2 mm from the mark made before bending, the test piece was evaluated as "A" (pass) and if it was 2 mm or more away, it was evaluated as "B" (fail).

[0029] "Flexibility" The composite cables of Examples 1 to 8 and Comparative Examples 1 and 2 were evaluated for flexibility. FIG. 11 is an explanatory diagram showing a method for measuring the flexibility of a composite cable. Each of the composite cables of Examples 1 to 8 and Comparative Examples 1 and 2 was cut to a length of 600 mm, and both ends were joined to obtain a ring-shaped specimen. The joining method for the both ends is not important, but the joined ends are joined so that the joined one end and the other end maintain the same orientation. For example, one end and the other end of the composite cable may be inserted into both ends of a short cylindrical member and connected so as not to come off, or the cable cores at both ends may be tied together with restraining devices or wires. The ring-shaped specimen was placed so that the central axis of the ring was horizontal, and a weight W with a hook was hung from the bottom of the specimen. Weight W applied a downward load of 2 kgf (19.6 N) to the specimen. Weight W was hung slowly so as not to apply an initial velocity to the specimen. As a result, the test specimen became an ellipse elongated in the vertical direction, and the value of the inner diameter S of the minor axis of the test specimen at this time was measured to evaluate flexibility. As a result, when the value of the minor axis inner diameter S was 12.5 [mm] or less, it was evaluated as "A" (pass), and when it exceeded 12.5 [mm], it was evaluated as "B" (fail).

[0030] [Results of each evaluation] With regard to "stability of cable core," Examples 1 to 8 and Comparative Example 2 were judged to be pass, while only Comparative Example 1 was judged to be fail. In Comparative Example 1, the pulling force of the cable core 20 from the outer sheath 4 was 50 [N], which is less than the lower limit of 60 [N] set by the present invention, and therefore it is presumed that the cable core 20 was prone to movement within the outer sheath 4 and could not be held stably.

[0031] With regard to "flexibility," Examples 1 to 8 and Comparative Example 1 were judged to be acceptable, while only Comparative Example 2 was judged to be unacceptable. In Comparative Example 2, the pull-out force of the cable core 20 from the outer sheath 4 was 100 [N], which exceeds the upper limit of 90 [N] set by the present invention. Therefore, it is presumed that the flexibility of the entire composite cable was impaired by excessively constraining the cable core 20 within the outer sheath 4.

[0032] From the above evaluation, it was concluded that when the outer sheath 4 covers the cable core 20 within a length range of 50 mm, by setting the pull-out force of the cable core 20 from the outer sheath 4 within the range of 60 N to 90 N, regardless of whether the cable has four or six cores and regardless of whether a pressure wrap 5 is used or not, it is possible to stably hold the cable core 20 within the outer sheath 4 against movement, vibration, etc. around the exterior of the composite cable 1, and to give the composite cable 1 appropriate flexibility.

[0033] [Technical Effects of the Embodiments of the Invention] In the above-mentioned composite cable 1, when the outer sheath 4 covers the cable core 20 within a length range of 50 mm, by setting the pull-out force of the cable core from the outer sheath to a range of 60 N or more and 90 N or less, it is possible to stably hold the cable core 20 within the outer sheath 4 against movement, vibration, etc. around the exterior of the composite cable 1 and to give the composite cable 1 appropriate flexibility. Furthermore, even when the composite cable 1 is configured to have a pressure wrap 5 for the cable core 20 inside the outer sheath 4, it is possible to stably hold the cable core 20 inside the outer sheath 4 and to give the composite cable 1 appropriate flexibility.

[0034] In particular, when the cable core 20 consists of two power wires 3 and a pair of twisted signal wires, the composite cable 1 can stably hold the cable core 20 within the outer sheath 4 and provide the composite cable 1 with appropriate flexibility. Similarly, when the cable core 20 consists of two power lines 3 and two pairs of twisted signal lines, the composite cable 1 can stably hold the cable core 20 within the outer sheath 4 and provide the composite cable 1 with appropriate flexibility.

[0035] [others] It goes without saying that the present invention is not limited to the above-described embodiments, and can be modified as appropriate without departing from the spirit of the present invention. For example, although the outer sheath 4 is formed in only one layer in FIGS. 2 and 3, it is also possible to form the outer sheath 4 in multiple layers.

[0036] Furthermore, the description of the materials of the resin layers 22, 32 and outer sheath 4 of the composite cable 1 in this embodiment is merely an example and is not limited to the above, and other materials that can ensure insulation and internal protection functions can be selected. [Explanation of symbols]

[0037] 1 composite cable 2 signal lines 20 cable cores 21 Conductor 22 Resin layer (insulating layer) 3 Power line 31 Conductor 32 Resin layer (insulating layer) 4 outer sheath 5 Pressing

Claims

1. a plurality of power lines each having an insulating layer around a conductor; at least one pair of twisted signal wires, each of which is formed by twisting together two signal wires having an insulating layer around the outer periphery of a conductor; a composite cable including a cable core formed by twisting all of the power supply wires and all of the twisted pair signal wires together, and an outer sheath formed around the outer periphery of the cable core, When the outer sheath covers the cable core within a length of 50 mm, the force required to pull out the cable core from the outer sheath is 60 N or more and 90 A composite cable characterized by having a thickness of [N] or less.

2. 2. The composite cable according to claim 1, wherein the cable core is held down by a winding inside the outer sheath.

3. 2. The composite cable according to claim 1, wherein the cable core comprises two of the power lines and one pair of the twisted signal lines.

4. 2. The composite cable according to claim 1, wherein the cable core comprises two of the power supply wires and two pairs of the twisted signal wires.

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