JP7740465B2 - Communication composite cable - Google Patents

Description

The present invention relates to a composite cable, and in particular to a communication composite cable having multiple communication cables.

Composite communication cables containing multiple communication cables are known. One example of a conventional composite communication cable is a jumper cable for railway vehicles that contains two or more LAN (Local Area Network) cables with different transmission bandwidths.

JP 2017-188249 A

The inventors discovered that return loss in a communications composite cable exceeds a predetermined reference value (peak value) at certain frequencies. Based on this discovery, they conducted further research and found that no abnormalities were observed in the return loss of the individual communications cables included in the communications composite cable. Specifically, when the return loss of multiple communications cables was measured individually before the composite cable was manufactured, no peak values were observed. On the other hand, in a communications composite cable in which multiple communications cables were twisted together and no peak values were observed, peak values were observed in at least one or more of the communications cables.

The inventors therefore conducted further research to create a communications composite cable in which return loss exceeding a specified standard value would not occur in any communications cable, and completed the present invention.

The objective of this invention is to create a composite communication cable in which no return loss exceeding the standard value occurs in any communication cable.

The composite communication cable of the present invention comprises a plurality of twisted communication cables. At least two of the plurality of communication cables comprise a plurality of twisted pairs of wires, each of which comprises a plurality of twisted insulated wires. The twisting directions of the plurality of communication cables, twisted pairs of wires, and insulated wires are the same.

In one aspect of the present invention, the composite communication cable includes a tension member, five of the communication cables arranged around the tension member, and a filler arranged around the tension member and the communication cables.

In another aspect of the present invention, the transmission bandwidth of three of the five communication cables is 600 MHz, and the transmission bandwidth of two of the five communication cables is 100 MHz.

This invention realizes a composite communication cable in which no return loss exceeding the standard value occurs in any of the communication cables.

1 is a cross-sectional view showing an example of a communication composite cable of the present invention. 2 is an explanatory diagram schematically illustrating the twist direction of the communication cable in the communication composite cable shown in FIG. 1 . FIG. 2 is an explanatory diagram illustrating the twisting direction of the twisted pair wires and the insulated wires in the communication composite cable shown in FIG. 1 . FIG.

An example of an embodiment of the composite communication cable of the present invention will be described below. The composite communication cable of this embodiment is a jumper cable that is installed across two railway cars. In the following description, the same reference numerals will generally be used for identical or substantially identical configurations, elements, etc.

The jumper cable 1 shown in FIG. 1 includes a tension member 10, multiple communication cables 20, a filler 30, a pressure tape 40, and a sheath 50. The jumper cable 1 according to this embodiment includes five communication cables 20. In the following description, the five communication cables 20 shown in FIG. 1 may be distinguished by being referred to as "communication cable 20a," "communication cable 20b," "communication cable 20c," "communication cable 20d," and "communication cable 20e." In other words, the five communication cables 20 included in the jumper cable 1 may be distinguished by their reference symbols. However, this distinction is made merely for the sake of convenience.

The tension member 10 is located at the center of the jumper cable 1 and includes a high-tension wire 11 and an elastic intervening layer 12 surrounding the high-tension wire 11. In this embodiment, the high-tension wire 11 is made of multiple twisted piano wires.

The elastic intervening layer 12 is formed from an elastomer. Specifically, the elastic intervening layer 12 is formed from a polyolefin-based elastomer. More specifically, the elastic intervening layer 12 is formed by extruding a polyolefin-based elastomer, which is a mixture of a polyolefin-based rubber such as ethylene propylene rubber and a resin such as polyethylene or polypropylene, around the high-tension wire 11.

The filler 30 is placed in the gap between the tension member 10 and the communication cable 20 and in the gap around the communication cable 20 so that the cross-sectional shape of the assembly of the tension member 10, communication cable 20, and filler 30 is circular or approximately circular. The filler 30 may be, for example, a fibrous or thread-like filler made of plastic, jute, or the like.

The five communication cables 20a, 20b, 20c, 20d, and 20e shown in Figure 1 are twisted in the same direction around the tension member 10 at a predetermined twist pitch. As a result, in the cross section of the jumper cable 1 (the cross section shown in Figure 1), the communication cables 20a, 20b, 20c, 20d, and 20e are arranged at equal or approximately equal intervals around the tension member 10 in the circumferential direction of the tension member 10.

As shown in Figure 2, the twist direction of the communication cables 20a, 20b, 20c, 20d, and 20e of the jumper cable 1 is right-handed. In other words, the communication cables 20a, 20b, 20c, 20d, and 20e are all right-handed (S-twisted). In the following description, the twist direction of the communication cable 20 of the jumper cable 1 may be referred to as the "first twist direction." Note that hatching and other markings present in Figure 1 have been omitted in Figure 2.

Referring again to Figure 1, of the five communication cables 20 shown, communication cables 20a, 20b, 20d, and 20e have the same basic structure. Specifically, communication cables 20a, 20b, 20d, and 20e each include four twisted pairs 21, an inner sheath 22, and a shielding layer 23 disposed around the twisted pairs 21. However, in communication cable 20a, the inner sheath 22 is disposed on the outside of the four twisted pairs 21, and the shielding layer 23 is disposed on the outside of the inner sheath 22. On the other hand, in communication cables 20b, 20d, and 20e, the shielding layer 23 is disposed on the outside of the four twisted pairs 21, and the inner sheath 22 is disposed on the outside of the shielding layer 23. Furthermore, shielding tape 27 is wrapped around each twisted pair 21 in communication cables 20b, 20d, and 20e, but no shielding tape is wrapped around each twisted pair 21 in communication cable 20a.

The four twisted pairs 21 of communication cables 20a, 20b, 20d, and 20e are twisted at a predetermined pitch, and the two insulated wires 24 that make up each twisted pair 21 are also twisted at a predetermined pitch. Furthermore, each insulated wire 24 that makes up each twisted pair 21 includes a conductor 25 and an insulating layer 26 that surrounds the conductor 25.

The communication cable 20c shown in Figure 1 comprises four insulated wires 24 twisted at a predetermined pitch. Each insulated wire 24 comprises a conductor 25 and an insulating layer 26 surrounding the conductor 25. A shielding layer 23 surrounds the four insulated wires 24, and an inner sheath 22 surrounds the shielding layer 23.

As shown in FIG. 3, the four twisted pairs 21 in communication cable 20a are right-handed (S-twisted). Although not shown, the four twisted pairs 21 in communication cables 20b, 20d, and 20e shown in FIG. 1 are also all right-handed (S-twisted). In the following description, the twist direction of the four twisted pairs 21 in each of communication cables 20a, 20b, 20d, and 20e may be referred to as the "second twist direction."

As shown in FIG. 3, the two insulated wires 24 that make up each twisted pair 21 in communication cable 20a are all right-handed (S-twisted). Although not shown, the two insulated wires 24 that make up each twisted pair 21 in communication cables 20b, 20d, and 20e shown in FIG. 1 are also all right-handed (S-twisted). In the following description, the twist direction of the two insulated wires 24 that make up each twisted pair 21 may be referred to as the "third twist direction." Note that hatching and other markings that are present in FIG. 1 are omitted in FIG. 3.

The communication cables 20a and 20c shown in FIG. 1 have different transmission bandwidths than the communication cables 20b, 20d, and 20e. Specifically, communication cable 20a is a Category 5 LAN cable (0.5 mm2 x 4P) with a transmission bandwidth of 100 MHz (compliant with IEC 61156-6). Meanwhile, communication cables 20b, 20d, and 20e are Category 7 LAN cables (AWG24 x 4P) with a transmission bandwidth of 600 MHz (compliant with IEC 61156-6). Furthermore, communication cable 20c is a Category 5 LAN cable (0.5 mm2 x 4C) with a transmission bandwidth of 100 MHz (compliant with IEC 61156-6). In other words, jumper cable 1 is an Ethernet®-based composite communication cable that includes two CAT5 LAN cables and three CAT7 LAN cables.

The thickness of the inner sheath 22 of each communication cable 20 is adjusted so that the outer diameters of the five communication cables 20 are the same or approximately the same. Here, the outer diameters of the five communication cables 20 being the same or approximately the same means that the difference between the outer diameter of each communication cable 20 and the average outer diameter of the five communication cables 20 is within a range of ±0.5 mm.

The inner sheath 22 of each communication cable 20 is extruded from polyolefin resin. The outermost layer (inner sheath 22 or shielding layer 23) of each communication cable 20 is in contact with the elastic intervening layer 12 of the tension member 10.

As described above, the five communication cables 20a, 20b, 20c, 20d, and 20e of the jumper cable 1 are right-handed (S-twisted). The four twisted pairs 21 of each of the communication cables 20a, 20b, 20d, and 20e are also right-handed (S-twisted). Furthermore, the two insulated wires 24 that make up each twisted pair 21 are also right-handed (S-twisted). Note that communication cable 20c does not have any twisted pairs 21. Therefore, the twist direction (second twist direction) of the twisted pairs 21 is not considered for communication cable 20c.

As described above, the jumper cable 1 according to this embodiment has multiple communication cables 20. Furthermore, in the jumper cable 1 according to this embodiment, the three twist directions, the first twist direction, the second twist direction, and the third twist direction, are all unified in the same direction (rightward).

When the return loss of the communication cable 20 included in the jumper cable 1 of this embodiment, which has the technical features described above, was measured, no peak values exceeding the specified reference value were detected. Specifically, when the return loss was measured when an electrical signal of a specified frequency was transmitted using each of the communication cables 20 included in the jumper cable 1, no return loss exceeding the reference value was detected for any of the communication cables 20.

For comparison, a communication composite cable was prepared in which only the first twist direction differed from the jumper cable 1 of this embodiment, and similar measurements were performed. The communication composite cable prepared had the second and third twist directions "right," while the first twist direction was "left." As a result, a return loss exceeding the reference value was detected.

The reference value (dB) is a value calculated by the following formula (1) when the frequency of the transmitted electrical signal is f (MHz).
25-8.6log(f/20) (however, 20≦f<600)...(Formula 1)
From the above measurement results, it was confirmed that the jumper cable 1 of this embodiment, in which the three twisting directions of the first twisting direction (twisting direction of the communication cable 20), the second twisting direction (twisting direction of the twisted pairs 21), and the third twisting direction (twisting direction of the insulated wires 24 constituting the twisted pairs 21) are the same, does not generate a return loss exceeding the reference value. Furthermore, from the above measurement results, it is inferred that in the jumper cable 1 of this embodiment, in which the three twisting directions of the first twisting direction, the second twisting direction, and the third twisting direction are the same, none of the twists of the communication cable 20, the twisted pairs 21, and the insulated wires 24 open, and therefore no abnormality in the return loss occurs.

The pressure tape 40 shown in Figure 1 is a resin tape, and the shielding tape 27 is a PET tape with aluminum vapor deposition. The sheath 50, which forms the outermost layer of the jumper cable 1, is made of a polyolefin elastomer.

The present invention is not limited to the above-described embodiment and can be modified in various ways without departing from the spirit of the present invention. For example, the communication cables included in the communication composite cable of the present invention are not limited to LAN cables. Furthermore, the number and types of communication cables can be modified as appropriate, provided that the following (1) and (2) are satisfied.
(1) It includes at least two communication cables with two or more twisted pairs of wires.
(2) Each of the twisted pairs includes two or more twisted insulated wires.

Furthermore, the three twist directions, i.e., the first twist direction, the second twist direction, and the third twist direction, need only be consistent, and the direction may be right-handed (S twist) or left-handed (Z twist).

The high-tension wire 11 shown in Figure 1 can be replaced with a steel wire other than piano wire. The elastic intervening layer 12 can also be formed from a polyolefin-based elastomer with a different composition than the above, and the elastic intervening layer 12 and sheath 50 can also be formed from a material other than a polyolefin-based elastomer.

REFERENCE SIGNS LIST 1 Jumper cable 10 Tension member 11 High tension wire 12 Elastic intervening layer 20, 20a, 20b, 20c, 20d, 20e Communication cable 21 Twisted pair wire 22 Inner sheath 23 Shielding layer 24 Insulated wire 25 Conductor 26 Insulating layer 27 Shielding tape 30 Intervening layer 40 Pressing tape

Claims (3)

A composite communication jumper cable having a plurality of twisted communication cables and laid across two railway cars,
At least two of the plurality of communication cables include a plurality of twisted pairs;
The communication cables include a Category 5 LAN cable and a Category 7 LAN cable,
Each of the twisted pairs comprises a plurality of twisted insulated wires,
The twist directions of the plurality of communication cables, twisted pair wires, and insulated wires are the same,
A communication composite jumper cable that does not generate a return loss exceeding the reference value (dB) calculated by the following formula, when the frequency of the electrical signal being transmitted is f (MHz).
25-8.6log(f/20) (however, 20≦f<600)...(formula) 2. The communication composite jumper cable according to claim 1,
Tension members and
five of the communication cables arranged around the tension member;
A composite communications jumper cable comprising the tension member and an interposer disposed around the communications cable. 3. The communication composite jumper cable according to claim 2,
The five communication cables are three Category 7 LAN cables and five Category 5 LAN cables, forming a composite communication jumper cable.