Communication cables and wire harnesses

Abstract

To provide a communication cable and a wire harness by which stabilization of transmission characteristics and improvement in terminal workability can be achieved.SOLUTION: A communication cable 1 is provided with a twisted pair wire TW formed by twisting together two core wires 10, each having a conductor 11 and an insulator 12 around the outer periphery thereof, a sheath 20 that is provided in a solid state on the outside of the twisted pair wire TW and is composed of resin whose main component is identical to resin contained in a material constituting the insulator 12, and a silicone oil layer 30 that is interposed between the twisted pair wire TW and the sheath 20 and is composed of silicone oil having a viscosity of 300 CS or more and 1000 CS or less. The adhesion force between the twisted pair wire TW and the sheath 20 is 5 N or more, and is equal to or less than the value N of the product of the cross-sectional area (mm2) of the insulator and the tensile strength (MPa) of the insulator.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a communication cable and a wire harness. [Background technology]

[0002] Conventionally, communication cables formed by twisting two wire cores and extruding a sheath are known. Such communication cables are manufactured by two methods: tube extrusion, in which the sheath is extruded into a tubular shape, and solid extrusion, in which the sheath is extruded solidly (see, for example, Patent Document 1).

[0003] In communication cables manufactured by tube extrusion, the sheath is tubular, which creates a gap between the twisted pair wire and the sheath, and the gap with the sheath and the positional relationship of the twisted pair wire are easily changed by external stress, which tends to result in unstable transmission characteristics. On the other hand, communication cables manufactured by solid extrusion tend to have more stable transmission characteristics than communication cables manufactured by tube extrusion. Therefore, the use of solid extrusion communication cables is being considered.

[0004] It is also known that by using the same type of material for the core insulator and sheath of a communication cable, the change in the dielectric constant and dielectric loss tangent of the entire cable is small even when affected by the temperature of the usage environment, and good transmission characteristics can be obtained. Therefore, the use of communication cables made by solid extrusion using the same type of material for the core insulator and sheath is being considered. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-155824 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in communication cables made by solid extrusion using the same material for the core insulator and sheath, the melting points of the materials are close, so the core insulator melts at the resin temperature during sheath extrusion, easily causing the insulator of the twisted pair wire to stick to the sheath.When the insulator of the twisted pair wire sticks to the sheath, it becomes difficult to strip the sheath alone during terminal processing.

[0007] To address this problem, it is conceivable to place a powdered lubricant such as talc around the twisted pair wire before solid extrusion, but in practice it is difficult to spread the powdered lubricant all around the twisted pair wire without any gaps, and in the end sticking occurs, making it difficult to say that terminal processability is good.

[0008] The present invention has been made to solve these conventional problems, and its object is to provide a communication cable and a wire harness that can stabilize transmission characteristics and improve terminal processability. [Means for solving the problem]

[0009] The communication cable according to the present invention comprises a twisted pair wire formed by twisting two wire cores, each having a conductor and an insulator surrounding the conductor, a sheath provided in a solid state on the outside of the twisted pair wire and made of a resin whose main component is the same as that of the insulator, and a silicone oil layer interposed between the twisted pair wire and the sheath and made of silicone oil having a viscosity of 300CS or more and 1000CS or less, In accordance with ISO19642-2, the contact section between the twisted pair wire and the sheath is 50 mm, and the twisted pair wire is inserted into a hole in a component having a hole of a size that the twisted pair wire can pass through and pulled until the twisted pair wire is separated from the sheath. The adhesive force between the twisted pair wire and the sheath is 5N or more, and the cross-sectional area of ​​the insulator (mm 2 ) × tensile strength of insulator (MPa)N or less.

[0010] A wire harness according to the present invention includes the above-described communication cable. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a communication cable and a wire harness that are capable of stabilizing transmission characteristics and improving terminal processability. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view showing an example of a wire harness including a communication cable according to an embodiment of the present invention. [Figure 2] FIG. 2 is a side view showing the communication cable shown in FIG. [Figure 3] 1 is a table showing communication cables according to Examples 1 to 3 and Comparative Examples 1 to 4. [Figure 4] 10 is a graph showing the characteristic impedance of the communication cable according to Comparative Example 1. [Figure 5] 10 is a graph showing transmission mode conversion characteristics of the communication cable according to Comparative Example 1. [Figure 6] 4 is a graph showing the characteristic impedance of the communication cable according to the first embodiment. [Figure 7] 4 is a graph showing transmission mode conversion characteristics of the communication cable according to the first embodiment. [Figure 8] 1 is a graph showing the adhesive strength for Examples 1 to 3 and Comparative Examples 2 to 4. DETAILED DESCRIPTION OF THE INVENTION

[0013] The present invention will be described below in accordance with preferred embodiments. Note that the present invention is not limited to the embodiments shown below and can be modified as appropriate without departing from the spirit of the present invention. In addition, in the embodiments shown below, some components are omitted from illustration and description, but it goes without saying that publicly known or well-known technologies are applied as appropriate to the details of the omitted technologies within the scope of the content described below.

[0014] Fig. 1 is a cross-sectional view showing an example of a wire harness including a communication cable according to an embodiment of the present invention, Fig. 2 is a side view showing the communication cable shown in Fig. 1.

[0015] As shown in FIG. 1, the wire harness WH according to this embodiment is a bundle of multiple electric wires W, and at least one of the multiple electric wires W (one circuit) is configured as a communication cable 1, which will be described in detail below.

[0016] Such a wire harness WH may include, for example, connectors (not shown) at both ends of the plurality of electric wires W, or may be wrapped with tape (not shown) to bundle the plurality of electric wires W. The wire harness WH may also include an exterior part (not shown) such as a corrugated tube.

[0017] The communication cable 1 includes a twisted pair wire TW and a sheath 20. The twisted pair wire TW is formed by twisting together a pair of wire cores 10 (i.e., two wire cores 10) as shown in Fig. 2. Each wire core 10 includes a conductor 11 and an insulator 12.

[0018] The conductor 11 is made of, for example, a copper alloy. In the example shown in Fig. 1, the conductor 11 is made of a plurality of wires, but is not limited to this and may be a single wire. Note that the conductor 11 is not limited to a copper alloy and may be made of pure copper, aluminum, or one plated with tin, silver, or the like.

[0019] The insulator 12 is a covering member that covers the periphery of the conductors 11, and is made of, for example, PP (Polypropylene). Note that in this embodiment, it is assumed that the insulator 12 is made of a PP-based resin (a resin whose main component is PP), but it is not limited to PP-based resins, and other resins such as PE (Polyethylene)-based resins may also be used.

[0020] The sheath 20 is an insulating member that covers the twisted pair wire TW and is provided solidly on the outside of the twisted pair wire TW as shown in Fig. 1. In particular, the sheath 20 is provided so as to fill the gaps S between the wire cores O that make up the twisted pair wire TW. Such a sheath 20 is made of a resin that has the same main component as the insulator 12. In other words, if the insulator 12 is a PP-based resin, the sheath 20 will also be made of a PP-based resin. For example, the insulator 12 is made of PP with few additives, and the sheath 20 is made of PP with added flame retardant for protection performance.

[0021] Furthermore, the communication cable 1 according to this embodiment includes a silicone oil layer 30. The silicone oil layer 30 is thinly interposed between the twisted pair wires TW and the sheath 20, and has a viscosity of 300 CS or more and 1000 CS or less.

[0022] Here, the insulator 12 and sheath 20 according to this embodiment have the same main components, although their formulations are slightly different. Therefore, if the insulator 12 is also exposed to high temperatures during extrusion molding of the sheath 20, the two tend to stick together. However, the communication cable 1 has a silicone oil layer 30 interposed between them, which makes sticking less likely to occur. In particular, the silicone oil layer 30 can be easily evenly positioned on the twisted pair wires TW by immersing the twisted pair wires TW in a silicone oil bath or by applying it by spraying. Therefore, the evenly positioned silicone oil layer 30 effectively makes the communication cable 1 according to this embodiment less likely to stick together.

[0023] Moreover, the viscosity of the silicone oil layer 30 in this embodiment is appropriately set to 300 CS or more and 1000 CS or less. Therefore, the adhesive force between the insulator 12 and the sheath 20 is 5 N or more, and the "cross-sectional area of ​​the insulator (mm 2 ) × tensile strength of insulator (MPa) × N or less. This allows the sheath 20 to be easily stripped during terminal processing, improving terminal processability. 2) is the total cross-sectional area of ​​the insulation of the two wire cores 10.

[0024] If the adhesive force is less than 5N, the twisted pair wire TW will be easily moved relative to the sheath 20 when the sheath 20 is stripped. This will cause the processing length to change, resulting in the termination being rejected. 2 If the adhesive strength exceeds "(MPa) × tensile strength of insulator (MPa)" N, the adhesive strength will be too high, and the insulator 12 will stretch or break during terminal processing, resulting in failure of terminal processing. On the other hand, if the adhesive strength is 5 N or more and "(cross-sectional area of ​​insulator (mm 2 If the value is equal to or less than "(MPa) × tensile strength of insulator (MPa)" N, the terminal processing will not be rejected as described above, and terminal processability will be improved.

[0025] Next, examples and comparative examples relating to the communication cable 1 according to this embodiment will be described. Fig. 3 is a table showing communication cables according to Examples 1 to 3 and Comparative Examples 1 to 4.

[0026] As shown in FIG. 3, the communication cables according to Examples 1 to 3 and Comparative Examples 1 to 4 have core conductors made of copper alloy, and the conductor cross-sectional area of ​​each core is 0.14 mm 2 The insulator of the wire core is made of a resin whose main component is PP, and the cross-sectional area of ​​the insulator of one wire core is 0.46 mm 2 Furthermore, the sheath is made of a resin whose main component is PP.

[0027] In Comparative Example 1, the sheath was formed by tube extrusion, and in Examples 1 to 3 and Comparative Examples 2 to 4, the sheath was formed by solid extrusion. 2 ) × tensile strength of insulator (MPa) was 50.6 N in all of Examples 1 to 3 and Comparative Examples 1 to 4.

[0028] The viscosity of the silicone oil before extrusion was 100CS in Comparative Example 2, 300CS in Example 1, and 500CS in Example 2. The viscosity of the silicone oil before extrusion was 1000CS in Example 3, 1200CS in Comparative Example 3, and 3000CS in Comparative Example 4. The silicone oil used was from the KF-96 series manufactured by Shin-Etsu Chemical. Since this series does not have a silicone oil with a viscosity of 1200CS, the silicone oil in Comparative Example 3 was prepared by mixing silicone oils with other viscosities.

[0029] Although silicone oil with such a viscosity is heated during extrusion, the time of heat application is, for example, less than 1 second, so the viscosity does not change.Therefore, the viscosity of silicone oil after extrusion is 100CS, 300CS, 500CS, 1000CS, 1200CS, and 3000CS in the order of Comparative Example 2, Example 1, Example 2, Example 3, Comparative Example 3, and Comparative Example 4.In addition, silicone oil was not used in Comparative Example 1.

[0030] For the communication cables according to the above-described Comparative Example 1 and Example 1, the characteristic impedance (CIDM) and the transmission mode conversion characteristic (LCTL), which indicate the transmission characteristics, were measured at the initial value and after clamping.

[0031] Fig. 4 is a graph showing the characteristic impedance of the communication cable according to Comparative Example 1, and Fig. 5 is a graph showing the transmission mode conversion characteristics of the communication cable according to Comparative Example 1. Note that both the graphs in Fig. 4 and Fig. 5 also show standard values ​​that should be satisfied.

[0032] As shown in Fig. 4, the initial value of the characteristic impedance of the communication cable according to Comparative Example 1 is approximately 100 Ω, which is within the standard range of 90 Ω to 110 Ω. However, after clamping, the tubular sheath is crushed, resulting in a deterioration in transmission characteristics, and the characteristic impedance changes at times of 1 ns, 7 ns, and 13 ns. In particular, at a time of 1 ns, the characteristic impedance deteriorates to near the lower limit of the standard value.

[0033] 5, the initial value of the transmission mode conversion characteristic of the communication cable according to Comparative Example 1 is below the standard value, satisfying the standard value. However, after clamping, the tubular sheath is crushed, leading to a deterioration in the transmission characteristics, and the standard value is exceeded in some frequency bands, such as below 4 MHz and around 30 MHz, resulting in unsatisfactory results.

[0034] Fig. 6 is a graph showing the characteristic impedance of the communication cable according to Example 1, and Fig. 7 is a graph showing the transmission mode conversion characteristics of the communication cable according to Example 1. Note that both the graphs of Fig. 6 and Fig. 7 also show standard values ​​that should be satisfied.

[0035] As shown in Figure 6, the initial value of the characteristic impedance of the communication cable according to Example 1 is approximately 100 Ω, which is within the standard range of 90 Ω to 110 Ω. Furthermore, the characteristic impedance remains almost unchanged even after clamping, which means that the transmission characteristics are maintained. This is because the sheath is fully extruded and is not crushed by the clamping.

[0036] 7, the initial value of the transmission mode conversion characteristic of the communication cable according to Example 1 is equal to or less than the standard value, satisfying the standard value. Furthermore, even after clamping, the transmission mode conversion characteristic does not exceed the standard value, resulting in a satisfactory result. This transmission mode conversion characteristic also shows good results, similar to those described above.

[0037] From the above, it was found that the transmission characteristics can be stabilized by making the sheath solid rather than tubular.

[0038] Referring again to Figure 3, for Examples 1 to 3 and Comparative Examples 2 to 4, the adhesion between the twisted pair wires and the sheath was measured, and the terminal processability was also evaluated. The adhesion was measured in accordance with ISO 19642-2, with the contact section between the twisted pair wires and the sheath set at 50 mm, by hooking the sheath through a hole of a size large enough for the twisted pair wires to pass through and pulling it. The terminal processability was evaluated based on whether deformation (elongation, etc.) or breakage of the insulator occurred when a blade was inserted into the sheath and processed to strip off only the sheath, and whether the twisted pair wires moved and shifted as the sheath was stripped off, and a pass / fail judgment was made.

[0039] There were five samples, and Figure 3 shows the average, maximum, and minimum adhesion values. Regarding terminal workability, samples for which terminal work passed were marked with a "Good" and samples for which terminal work failed were marked with an "X." The minimum adhesion value is thought to be when the largest amount of silicone oil was applied, and the maximum adhesion value is thought to be when the smallest amount of silicone oil was applied. In both cases, the silicone oil only varied within the range of the appropriate amount applied.

[0040] FIG. 8 is a graph showing the adhesive strength for Examples 1 to 3 and Comparative Examples 2 to 4.

[0041] 3 and 8, the average value of the adhesion force for Comparative Example 2 was 51.2 N, the maximum value was 58 N, and the minimum value was 43 N. Of these, the terminal processing was rejected for at least the maximum value.

[0042] In addition, the average value of the adhesive strength in Example 1 was 24.6 N, the maximum value was 32 N, and the minimum value was 15 N. In Example 1, the terminal processing of all samples was acceptable.

[0043] In addition, the average value of the adhesive strength in Example 2 was 17.0 N, the maximum value was 24 N, and the minimum value was 12 N. In Example 2 as well, all samples passed the end processing.

[0044] In addition, the average value of the adhesive strength in Example 3 was 12.2 N, the maximum value was 16 N, and the minimum value was 10 N. In Example 3 as well, all samples passed the end processing.

[0045] In Comparative Example 3, the average value of the adhesive strength was 6.8 N, the maximum value was 10 N, and the minimum value was 3 N. Of these, the terminal processing was rejected for at least the minimum value.

[0046] For Comparative Example 4, the average value of the adhesion force was 2.4 N, the maximum value was 5 N, and the minimum value was 1 N. Of these, only the one with the maximum value passed the terminal processing, and all the others failed the terminal processing.

[0047] Here, since the terminal processing passed for the specimen with the highest adhesion force in Comparative Example 4, it was found that an adhesion force of at least 5N or more was necessary. In addition, the occurrence of failure in terminal processing due to breakage or excessive stretching of the insulator is theoretically related to the "cross-sectional area of ​​the insulator (mm 2 It was thought that the required value was 50.6 N or less. When Comparative Example 2 was examined, it was also found that the theoretical value of 50.6 N was the boundary between pass and fail for terminal processing.

[0048] In particular, it was found that the above-mentioned adhesive strength can be easily achieved if the viscosity of the silicone oil is 300 CS or more and 1000 CS or less before extrusion and 300 CS or more and 1000 CS or less after extrusion.

[0049] In this way, the communication cable 1 and wire harness WH according to this embodiment include the twisted pair wires TW and the sheath 20 that is provided in a solid state, so that the transmission characteristics are less likely to change due to external stress, and the transmission characteristics can be stabilized. Furthermore, the communication cable 1 and wire harness WH include the silicone oil layer 30 made of silicone oil, which is easier to distribute evenly around the twisted pair wires TW by application or the like compared to powdered lubricants. Moreover, the viscosity of the silicone oil is set to 300CS or more and 1000CS or less, so that the adhesive force between the twisted pair wires TW and the sheath 20 is 5N or more, and the "insulator cross-sectional area (mm 2 ) × insulator tensile strength (MPa) × insulator tensile strength (MPa) × N or less. This optimizes the viscosity of the silicone oil, preventing, for example, a situation in which the adhesion is too low and the twisted pair wire TW moves during terminal processing, resulting in a misalignment of the wire core length and resulting in a failure of the terminal processing. Conversely, it prevents a situation in which the adhesion is too high and the insulator 12 stretches or breaks during terminal processing, resulting in a failure of the terminal processing. This therefore stabilizes the transmission characteristics and improves terminal processing ease.

[0050] The present invention has been described above based on the embodiments, but the present invention is not limited to the above embodiments, and modifications may be made within the scope of the spirit of the present invention, and if possible, publicly known or well-known technologies may be combined. [Explanation of symbols]

[0051] 1: Communication cable 10: Core 11: Conductor 12: Insulator 20: Sheath 30: Silicone oil layer TW: Twisted pair wire WH: Wire harness

Claims

1. a twisted pair wire in which two wire cores, each having a conductor and an insulator surrounding the conductor, are twisted together; a sheath provided in a solid state on the outer side of the twisted pair wires and made of a resin whose main component is the same as that of the insulator; a silicone oil layer interposed between the twisted pair wires and the sheath, the silicone oil layer being made of silicone oil having a viscosity of 300 CS or more and 1000 CS or less; In accordance with ISO19642-2, the contact section between the twisted pair wire and the sheath is 50 mm, the twisted pair wire is inserted into a hole in a member having a hole of a size that the twisted pair wire passes through, and pulled, and the contact force between the twisted pair wire and the sheath required to pull out the twisted pair wire until it separates from the sheath is 5 N or more, and the cross-sectional area of ​​the insulator (mm ２ ) × tensile strength of insulator (MPa)N or less A communication cable characterized by:

2. A wire harness comprising the communication cable according to claim 1.

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