Multi-core cable

Abstract

To provide a multi-core cable that has excellent external appearance and from which a drain wire can be easily drawn out.SOLUTION: A multi-core cable 1 comprises: an assembly core 3 which is formed by stranding plural electric wires 2; a tape member 4 which is spirally wound to a periphery of the assembly core 3; a shield layer 5 which is provided so as to cover a periphery of the tape member 4; and a sheath 6 which covers a periphery of the shield layer 5, where the shield layer 5 is constituted of a laterally wound shield by spirally winding plural shield-use strands 5a and one or more drain wires 7 made up of a single-wire conductor around the tape member 4, the drain wire 7 is made up of a stranded wire formed by stranding plural strands 7a, and a cross-section area of the drain wire 7 is 0.9 times or more and 1.3 times or less a cross-section area of the shield-use strands 5a.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] There is known a multi-core cable in which a shield layer is provided so as to collectively cover an aggregate core in which a plurality of electric wires are twisted together. In such a multi-core cable, a drain wire electrically connected to the shield layer may be provided in order to facilitate grounding of the shield layer (for example, connection to a ground electrode of a substrate) (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Utility Model Application Publication No. 7-14516 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when a drain wire is provided, the outer peripheral surface of the cable at the portion where the drain wire is provided is raised, which causes a problem that the appearance of the cable is deteriorated. Also, it is desirable for the drain wire to be easy to pull out during terminal processing.

[0005] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to provide a multi-core cable which has a good appearance and from which drain wires can be easily pulled out. [Means for solving the problem]

[0006] The present invention aims to solve the above-mentioned problems by providing a multi-core cable comprising: an aggregate core formed by twisting together a plurality of electric wires; a tape member wound spirally around the aggregate core; a shielding layer provided to cover the periphery of the tape member; and a sheath covering the periphery of the shielding layer, wherein the shielding layer is composed of a shielding wire made of a solid conductor and a horizontally wound shield in which one or more drain wires are wound spirally around the tape member, the drain wire is made of a twisted wire formed by twisting together a plurality of wires, and the cross-sectional area of ​​the drain wire is 0.9 to 1.3 times the cross-sectional area of ​​the shielding wire. Effect of the Invention

[0007] According to the present invention, it is possible to provide a multi-core cable which has a good appearance and from which drain wires can be easily pulled out. [Brief description of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view showing a cross section perpendicular to the longitudinal direction of a multi-core cable according to an embodiment of the present invention. [Diagram 2] 10 is a cross-sectional view showing a cross section perpendicular to the longitudinal direction of a multi-core cable according to a modified example of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] [Embodiment Mode] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0010] 1 is a cross-sectional view perpendicular to the longitudinal direction of a multi-core cable 1 according to the present embodiment. Multi-core cable 1 is used, for example, as a cable for connecting an electronic device and a control device, and is used for signal transmission and power supply.

[0011] As shown in FIG. 1, the multi-core cable 1 includes an aggregate core 3 formed by twisting together a number of electric wires 2, a tape member 4 wound spirally around the aggregate core 3, a shielding layer 5 provided to cover the periphery of the tape member 4, and a sheath 6 covering the periphery of the shielding layer 5.

[0012] (Electric wire 2) The electric wire 2 is an insulated electric wire having a conductor 21 made of a twisted conductor formed by twisting together a plurality of wires, and an insulator 22 covering the conductor 21. However, the present invention is not limited to this, and the electric wire 2 may be, for example, a coaxial wire having a shield layer and a sheath further around the insulator 22. The electric wire 2 may also be a twisted pair wire formed by twisting together a pair of insulated electric wires, or a multi-core wire formed by collectively covering a plurality of insulated electric wires (or a plurality of conductors 21) with a sheath. The conductor 21 is a copper or copper alloy wire.

[0013] (Collective Core 3) The collective core 3 is formed by twisting together a plurality of electric wires 2. Here, a fibrous interposer 8 is disposed at the center of the cable, and six electric wires 2 and the interposer 8 are twisted around it to form the collective core 3. However, the number of electric wires 2 and the specific structure of the collective core 3 are not limited to this. The collective core 3 may be formed by twisting together a plurality of electric wires 2 in multiple layers. Although FIG. 1 shows a case in which all electric wires 2 constituting the collective core 3 have the same structure, electric wires 2 having different structures may be included. For example, the electric wires 2 may include, in addition to insulated electric wires, twisted pair wires, coaxial wires, etc.

[0014] (Tape member 4) The tape member 4 plays a role in preventing the aggregate core 3 from untwisting, and is made of a resin tape such as PET (polyethylene terephthalate), a paper tape, a nonwoven fabric tape, etc. The tape member 4 is wound around the aggregate core 3 in a spiral shape.

[0015] (Sheath 6) A shield layer 5 is provided so as to cover the periphery of the tape member 4, and a sheath 6 is provided so as to cover the shield layer 5. The sheath 6 plays a role in protecting the collective core 3 and the shield layer 5. The material of the sheath 6 is not particularly limited, and for example, PVC (polyvinyl chloride), fluororesin, etc. can be used. In order to make it easier to remove the sheath 6 during terminal processing and to make it easier to pull out the drain wire 7 described below, it is desirable to form the sheath 6 by tube extrusion.

[0016] (Shield layer 5) The shielding layer 5 is provided so as to cover the periphery of the tape member 4. The shielding layer 5 is composed of a horizontally wound shield in which a plurality of shielding wires 5a made of a solid conductor and one or more drain wires 7 are spirally wound around the periphery of the tape member 4. In this embodiment, the shielding layer 5 is composed of one drain wire 7 and 42 shielding wires 5a.

[0017] The drain wire 7 is used to ground the shield layer 5. By connecting the drain wire 7 to, for example, a ground electrode of the substrate, the entire shield layer 5 is grounded via the drain wire 7. In this embodiment, since the drain wire 7 is included in the horizontally wound shield, the drain wire 7 can be easily drawn out compared to, for example, a case in which the drain wire 7 is provided between the tape member 4 and the shield layer 5.

[0018] The drain wire 7 is made of a stranded wire formed by twisting together a number of strands 7a, and the cross-sectional area of ​​the drain wire 7 (the total cross-sectional area of ​​the strands 7a) is between 0.9 and 1.3 times the cross-sectional area of ​​one shielding strand 5a. This makes the outer diameter of the drain wire 7 and the outer diameter of the shielding strand 5a equal, making it possible to prevent the provision of the drain wire 7 from causing a bulge on the outer periphery of the cable. Furthermore, by forming the drain wire 7 from a stranded wire, it becomes easier to distinguish it from the shielding strand 5a.

[0019] In order to facilitate soldering of the drain wire 7 to a substrate or the like, the wires 7a constituting the drain wire 7 are preferably made of copper or a copper alloy wire. The shielding wires 5a may be made of aluminum or an aluminum alloy wire. This allows the multi-core cable 1 to be lightweight, and also facilitates soldering of the drain wires 7 for grounding the shielding layer 5.

[0020] When the shielding wire 5a is made of aluminum or aluminum alloy wire, the outer diameter of the shielding wire 5a is preferably 0.12 mm or more and 0.50 mm or less. This is because if the outer diameter of the shielding wire 5a is less than 0.12 mm, the wire is more likely to break and the electrical conductivity is lowered, and if the outer diameter exceeds 0.5 mm, the flexibility of the multi-core cable 1 is reduced. The twist pitch of the shielding layer 5 is preferably 10 times or more and 30 times or less than the lower diameter (the outer diameter of the tape member 4). This is because if the twist pitch of the shielding layer 5 is less than 10 times the lower diameter (the outer diameter of the tape member 4), the wire is wound very tightly and is more likely to break, and if it exceeds 30 times, the shielding wire 5a is more likely to break when the multi-core cable 1 is bent, and the wire is also more likely to have a bending habit. The twist pitch of the shielding layer 5 is the interval along the cable longitudinal direction between the points of any shielding wire 5a that are located at the same circumferential position of the cable.

[0021] When the wires 7a constituting the drain wire 7 are copper or copper alloy wires and the shielding wires 5a are aluminum or aluminum alloy wires, in order to suppress electrolytic corrosion, it is desirable to tin-plate the surfaces of the wires 7a constituting the drain wire 7. When tin-plated, the wires turn silver and become difficult to distinguish from aluminum or aluminum alloy wires, but in this embodiment, the drain wire 7 is made of twisted wires and can be easily distinguished.

[0022] Furthermore, the plating layer may be made of a CuSn alloy by performing heat treatment after tin plating. That is, the wires 7a constituting the drain wire 7 may have a plating layer made of a CuSn alloy on their surfaces. This makes it possible to further suppress the occurrence of electrolytic corrosion.

[0023] The drain wire 7 may be formed by stranding a plurality of strands 7a together. This makes it easier for the drain wire 7 to be deformed (crushed) by external forces, as compared to a case where the drain wire 7 is formed by concentric stranding, and makes it possible to more effectively prevent the outer surface of the cable from swelling up at the position where the drain wire 7 is provided. Furthermore, by making the cross-sectional area of ​​the drain wire 7 larger than that of the shielding strands 5a, the gap between the drain wire 7 and the adjacent shielding strands 5a can be filled by the deformation (crush) of the drain wire 7, thereby making it possible to maintain low contact resistance between the two.

[0024] If the drain wire 7 is made of a solid wire, it is likely to break when it is bent when connected to a substrate or when a load such as bending is applied to the drain wire 7 due to an external force being applied to the substrate, which is not preferable from the viewpoint of connection reliability. By making the drain wire 7 of a twisted wire as in the present embodiment, breaks are less likely to occur and connection reliability can be improved.

[0025] The outer diameter of the strands 7a constituting the drain wire 7 is preferably 0.03 mm or more and 0.13 mm or less. If the outer diameter of the strands 7a is less than 0.03 mm, the strands 7a are more likely to break, and it is necessary to use a large number of strands 7a to ensure the conductor cross-sectional area, which increases the cost. If the outer diameter of the strands 7a is more than 0.13 mm, the drain wire 7 is less likely to deform (collapse), and the portion where the drain wire 7 is provided is more likely to bulge on the outer circumferential surface of the cable.

[0026] The twist pitch of the drain wire 7 is preferably 50 to 150 times the outer diameter of the wires 7a constituting the drain wire 7. If the twist pitch of the drain wire 7 is less than 50 times the outer diameter of the wires 7a, the drain wire 7 is less likely to be crushed and unevenness is likely to occur on the outer peripheral surface of the multi-core cable 1, whereas if it exceeds 150 times, the wires 7a are likely to come apart, making soldering difficult. The twist pitch of the drain wire 7 is the interval along the longitudinal direction of the drain wire between points where any wires 7a are in the same position in the circumferential direction of the drain wire 7.

[0027] The number of the strands 7a constituting the drain wire 7 is preferably 7 or more and 40 or less. This is because if the number of strands 7a constituting the drain wire 7 is less than 7, the drain wire 7 is less likely to be crushed, the outer peripheral surface of the multi-core cable 1 is more likely to be uneven, and soldering is more difficult (i.e., some strands 7a are not wetted with solder, which reduces connection reliability and weakens the wires when pulled (external forces such as pulling and bending)). If the number of strands 7a constituting the drain wire 7 is less than 7, the number of strands 7a in contact with the seed strands 5a adjacent in the circumferential direction is too small, which may increase the contact resistance. If the number of strands 7a constituting the drain wire 7 is more than 40, the twist of the drain wire 7 is more likely to be disordered (stretching of the strands 7a is more likely to occur), and the cost is higher.

[0028] The twisting direction of the collective core 3 and the twisting direction of the shielding layer 5 are preferably the same. This makes it possible to obtain a multi-core cable 1 that is easy to bend and wire. However, when the twisting direction of the collective core 3 and the twisting direction of the shielding layer 5 are the same, it is desirable to make the twisting pitch of the collective core 3 different from the twisting pitch of the shielding layer 5 in order to prevent the shielding wires 5a and the drain wires 7 from entering the valleys between the electric wires 2 adjacent in the circumferential direction of the collective core 3 and deteriorating the appearance of the multi-core cable 1. The twisting direction of the collective core 3 is the direction in which the electric wires 2 rotate from one end to the other end when viewed from one end of the multi-core cable 1. The twisting direction of the shielding layer 5 is the direction in which the shielding wires 5a and the drain wires 7 rotate from one end to the other end when viewed from one end of the multi-core cable 1. The twisting pitch of the collective core 3 is the interval along the cable longitudinal direction between the points where any electric wires 2 are located at the same position in the cable circumferential direction.

[0029] When wiring the multi-core cable 1 through a movable part to which repeated bending, twisting, and other operations are applied, it is desirable that the twist pitch of the shield layer 5 is smaller than the twist pitch of the assembled core 3. This makes it possible to reduce the amount of aluminum, which has low flexibility, used when the shielding wires 5a that mainly constitute the shield layer 5 are made of aluminum or aluminum alloy wires, and thus makes it possible to suppress a decrease in the flexibility of the multi-core cable 1.

[0030] On the other hand, when the multi-core cable 1 is used as fixed wiring that maintains the bent shape at the time of installation, it is desirable that the twist pitch of the shield layer 5 is larger than the twist pitch of the assembled core 3. This makes it possible to increase the amount of aluminum used, which has the property of being less likely to return to its original shape after bending, when the shielding wires 5a that mainly constitute the shield layer 5 are made of aluminum or aluminum alloy wires, and makes it easier to hold the multi-core cable 1 in a bent state.

[0031] The twisting direction of the shield layer 5 and the twisting direction of the drain wire 7 are preferably the same. This makes it possible to prevent the drain wire 7 from being crushed and from being lifted up. The twisting direction of the drain wire 7 is the direction in which the wires 7a rotate around the center of the drain wire 7 from one end to the other end when viewed from one end of the multi-core cable 1.

[0032] (Modification) In the present embodiment, the case where the shield layer 5 includes one drain wire 7 has been described, but the present invention is not limited thereto, and the shield layer 5 may include multiple drain wires 7, for example, as shown in FIG. 2. By using multiple drain wires 7, it is possible to ensure the cross-sectional area of ​​the entire drain wires 7 while suppressing the bulge of the cable outer surface. For example, when the outer diameter of the shielding wires 5a is reduced in order to reduce the outer diameter of the cable, it is considered that the cross-sectional area of ​​one drain wire 7 is insufficient. In such a case, it is possible to ensure the cross-sectional area of ​​the entire drain wires 7 by using multiple drain wires 7.

[0033] In the example of Fig. 2, a plurality of drain wires 7 (two in this case) are arranged adjacent to each other in the circumferential direction of the cable. This allows a plurality of drain wires 7 (two in this case) to be connected together to a substrate or the like, facilitating the work of connecting the drain wires 7. However, this is not limiting, and for example, two drain wires 7 may be arranged to face each other across the center of the cable. Furthermore, when a plurality of drain wires 7 are used, it is not necessary to connect all of the drain wires 7 to a substrate or the like, and the drain wires 7 that are not used for grounding may be included in the shield layer 5.

[0034] (Functions and Effects of the Embodiments) As described above, in the multi-core cable 1 according to this embodiment, the shielding layer 5 is composed of a horizontally wound shield in which multiple shielding wires 5a made of solid conductors and one or more drain wires 7 are spirally wound around the tape member 4, and the drain wire 7 is made of a twisted wire in which multiple wires 7a are twisted together, and the cross-sectional area of ​​the drain wire 7 is 0.9 to 1.3 times the cross-sectional area of ​​the shielding wires 5a.

[0035] By including the drain wire 7 in the shield layer 5, the drain wire 7 can be easily drawn out. Furthermore, by forming the drain wire 7 as a stranded wire, it is easy to distinguish it from the shielding wire 5a made of a solid conductor, and the contact area with the adjacent shielding wire 5a can be increased to reduce the contact resistance. Furthermore, by forming the drain wire 7 as a stranded wire, the drain wire 7 is less likely to break even if it is bent when drawing out and connecting it to a board or the like, and the connection work of the drain wire 7 is easier and the connection reliability can be improved compared to the case where the drain wire 7 is formed of a solid conductor. Furthermore, by making the cross-sectional area of ​​the drain wire 7 and the shielding wire 5a equal, the cable outer surface is prevented from swelling at the part where the drain wire 7 is provided, and the appearance of the multi-core cable 1 can be improved. Furthermore, according to this embodiment, the outer surface of the multi-core cable 1 becomes close to a circular shape, so that the problem of the multi-core cable 1 being difficult to bend in a specific direction is eliminated, and a multi-core cable 1 that is easy to wire can be realized.

[0036] (Summary of the embodiment) Next, the technical ideas grasped from the above-described embodiment will be described by using the reference numerals and the like in the embodiment. However, the reference numerals and the like in the following description do not limit the components in the claims to the members and the like specifically shown in the embodiment.

[0037] [1] A multi-core cable (1) comprising: an aggregate core (3) in which a plurality of electric wires (2) are twisted together; a tape member (4) wound in a spiral shape around the aggregate core (3); a shielding layer (5) provided so as to cover the periphery of the tape member (4); and a sheath (6) covering the periphery of the shielding layer (5), wherein the shielding layer (5) is composed of a horizontally wound shield in which a plurality of shielding wires (5a) made of solid conductors and one or more drain wires (7) are wound in a spiral shape around the tape member (4), and the drain wires (7) are made of a twisted wire in which a plurality of wires (7a) are twisted together, and the cross-sectional area of ​​the drain wires (7) is 0.9 to 1.3 times the cross-sectional area of ​​the shielding wires (5a).

[0038] [2] The multi-core cable (1) according to [1], wherein the drain wire (7) is formed by stranding a plurality of strands (7a), and the cross-sectional area of ​​the drain wire (7) is larger than the cross-sectional area of ​​the shielding strands (5a).

[0039] [3] The multi-core cable (1) according to [1] or [2], wherein the wires (7a) constituting the drain wire (7) are made of copper or a copper alloy wire, and the shielding wires (5a) are made of aluminum or an aluminum alloy wire.

[0040] [4] The multi-core cable (1) according to [3], wherein the wires (7a) constituting the drain wire (7) have a surface that is tin-plated.

[0041] [5] The multi-core cable (1) according to [3], wherein the wires (7a) constituting the drain wire (7) have a plating layer made of a CuSn alloy on their surfaces.

[0042] [6] The multi-core cable (1) according to any one of [1] to [5], wherein the shielding layer (5) includes a plurality of the drain wires (7), and the plurality of the drain wires (7) are arranged adjacent to each other in a circumferential direction of the cable.

[0043] (Additional Note) Although the embodiment of the present invention has been described above, the invention according to the claims is not limited to the embodiment described above. It should be noted that not all of the combinations of features described in the embodiment are essential to the means for solving the problems of the invention. The present invention can be modified appropriately without departing from the spirit of the invention. [Explanation of symbols]

[0044] 1...Multi-core cable 2...Electric wire 3. Collective core 4…Tape member 5…Shield layer 5a…Shielding wire 6…Sheath 7…Drain wire 7a…Element wire

Claims

1. A core made by twisting together a plurality of electric wires; a tape member wound helically around the collective core; a shielding layer provided so as to cover the periphery of the tape member; a sheath covering the shield layer, the shield layer is composed of a horizontally wound shield in which a plurality of shielding wires each made of a solid conductor and one or more drain wires are spirally wound around the tape member, The drain wire is made of a stranded wire formed by stranding a plurality of wires, The cross-sectional area of ​​the drain wire is 0.9 to 1.3 times the cross-sectional area of ​​the shield wire. Multicore cable.

2. The drain wire is configured by stranding a plurality of wires, The cross-sectional area of ​​the drain wire is larger than the cross-sectional area of ​​the shield wire.

2. The multi-conductor cable of claim 1.

3. The wire constituting the drain wire is made of copper or a copper alloy wire, The shielding wire is made of aluminum or an aluminum alloy wire.

2. The multi-conductor cable of claim 1.

4. The surface of the wire constituting the drain wire is tin-plated.

4. The multi-core cable according to claim 3.

5. The wire constituting the drain wire has a plating layer made of a CuSn alloy on its surface.

4. The multi-core cable according to claim 3.

6. The shield layer includes a plurality of the drain wires, and the plurality of the drain wires are arranged adjacent to each other in a circumferential direction of the cable.

2. The multi-conductor cable of claim 1.

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