Multicore cable

Abstract

To provide a multicore cable that has excellent external appearance and can be easily wired.SOLUTION: A multicore cable 1 comprises: an assembly core 3 in which a plurality of electric wires 2 are stranded; a tape member 4 which is spirally wound to the periphery of the assembly core 3; a shield layer 5 which is provided so as to cover the periphery of the tape member 4; a drain wire 7 which is provided between the tape member 4 and the shield layer 5; and a sheath 6 which covers the periphery of the shield layer 5, where the drain wire 7 is made of a stranded wire in which a plurality of element wires 7a are stranded, and is provided in the same direction and at the same pitch as strand of the assembly core 3, and the drain wire 7 is provided so as to enter a valley portion 8 between the electric wires 2 adjacent to each other in a circumferential direction on the outermost layer of the assembly core 3 together with a part of the tape member 4 on the periphery of the drain wire 7.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 number 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 Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2001-110250 A [Patent Document 2] JP 2009-245713 A 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 portion where the drain wire is provided is raised, which causes a problem of deteriorating the appearance of the cable. In addition, when a portion of the outer peripheral surface of the cable is raised and the cross-sectional shape becomes non-circular, it may become difficult to bend the cable in a specific direction, which may make wiring difficult.

[0005] SUMMARY OF THE PRESENT EMBODIMENTS Accordingly, an object of the present invention is to provide a multi-core cable that has a good appearance and is easy to wire. [Means for solving the problem]

[0006] The present invention has an object 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 so as to cover the periphery of the tape member; a drain wire provided between the tape member and the shielding layer; and a sheath covering the periphery of the shielding layer, wherein the drain wire is made of a twisted wire formed by twisting together a plurality of elemental wires and is provided in the same direction and at the same pitch as the twisting of the aggregate core, and the drain wire, together with a part of the tape member surrounding the drain wire, is provided so as to enter a valley portion between circumferentially adjacent electric wires in the outermost layer of the aggregate core. Effect of the Invention

[0007] According to the present invention, it is possible to provide a multi-core cable that has a good appearance and is easy to wire. [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. 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, a sheath 6 covering the periphery of the shielding layer 5, and a drain wire 7 provided between the tape member 4 and the shielding layer 5.

[0012] (Electric wire 2) The electric wire 2 is an insulated electric wire having a conductor 21 made of a stranded conductor in which a plurality of wires are stranded together, and an insulator 22 covering the conductor 21. The wires constituting the conductor 21 may be made of copper or a copper alloy wire. However, the present invention is not limited thereto, and the electric wire 2 may be, for example, a coaxial wire having a shield layer and a sheath around the insulator 22. The electric wire 2 may be a twisted pair wire in which a pair of insulated electric wires are twisted together, or a multi-core wire in which a plurality of insulated electric wires (or a plurality of conductors 21) are collectively covered with a sheath. In this embodiment, the electric wire 2 has an outer diameter of 0.6 mm or more. This is because if the outer diameter of the electric wire 2 is less than 0.6 mm, the volume of the valley portion 8 between the electric wires 2 adjacent in the circumferential direction becomes too small, making it difficult to arrange the drain wire 7 in the valley portion 8.

[0013] (Collective Core 3) The collective core 3 is formed by twisting together a plurality of electric wires 2. Here, a case is shown in which the collective core 3 is formed by twisting together four electric wires 2, but the number of electric wires 2 is not limited to this. The collective core 3 may also be formed by twisting together a plurality of electric wires 2 in multiple layers. In addition, while FIG. 1 shows a case in which all the 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 holding the collective core 3 from untwisting, and is made of a resin tape such as PET (polyethylene terephthalate), a paper tape, a nonwoven tape, or the like. The tape member 4 is wound around the collective core 3 in a spiral shape. The winding direction of the tape member 4 is the same as the twisting direction of the collective core 3. This makes it easier for the tape member 4 to enter the valley portion 8 between the electric wires 2 adjacent in the circumferential direction in the outermost layer of the collective core 3 when the drain wire 7 is provided. The winding direction of the tape member 4 is the direction in which the tape member 4 rotates from one end to the other end of the multi-core cable 1 when viewed from the other end 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 the other end to the one end when viewed from the one end of the multi-core cable 1.

[0015] In addition, the winding pitch of the tape member 4 is desirably approximately equal to the twist pitch of the collective core 3, and is preferably 0.8 to 1.2 times the twist pitch of the collective core 3. Furthermore, it is more desirably equal to the twist pitch of the collective core 3. As a result, the tape member 4 is wound around the electric wires 2, and the tape member 4 is more likely to enter the valley portion 8. The winding pitch of the tape member 4 is the interval along the cable longitudinal direction at the points where the tape members 4 are at the same position in the cable circumferential direction. Similarly, the twist pitch of the collective core 3 is the interval along the cable longitudinal direction at the points where any electric wires 2 are at the same position in the cable circumferential direction. In addition, the thickness of the tape member 4 is desirably 12 μm to 100 μm. If the thickness of the tape member 4 is less than 12 μm, the tape member 4 may be torn by the drain wire 7. If the thickness of the tape member 4 is more than 100 μm, the tape member 4 is less likely to enter the valley portion 8.

[0016] (Shield layer 5) The shield layer 5 is provided so as to cover the periphery of the tape member 4. The shield layer 5 is formed, for example, using a plurality of metal wires. In this embodiment, the shield layer 5 is formed of a braided shield in which a plurality of metal wires are braided. However, the present invention is not limited to this, and the shield layer 5 may be a horizontally wound shield in which a plurality of metal wires are wound in a spiral shape. In this embodiment, a braided shield using aluminum or aluminum alloy wires as the metal wires is used as the shield layer 5. This allows the multi-core cable 1 to be lightweight. In addition, the shield layer 5 may be formed, for example, of an interwoven braid using a first wire made of aluminum or aluminum alloy wire and a second wire made of copper or copper alloy wire, or a copper foil thread.

[0017] (Drain wire 7) The drain wire 7 is used to ground the shield layer 5, and is provided so as to be in direct contact with and electrically connected to the shield layer 5. By connecting the drain wire 7 to, for example, a ground electrode of the substrate, the shield layer 5 is grounded via the drain wire 7. In this embodiment, 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. To facilitate soldering to a substrate or the like, the strands 7a constituting the drain wire 7 are preferably made of copper or a copper alloy. When aluminum or an aluminum alloy wire is used for the shield layer 5 to reduce weight, the surface of the strands 7a is preferably tin-plated to suppress electrolytic corrosion.

[0019] In the multi-core cable 1 according to the present embodiment, the drain wire 7, together with a part of the tape member 4 around the drain wire 7, is provided so as to enter into a valley portion (recessed portion) 8 between circumferentially adjacent electric wires 2 in the outermost layer of the collective core 3. That is, the drain wire 7 is provided in a region surrounded by a part of the tape member 4 provided so as to enter into the valley portion 8 between circumferentially adjacent electric wires 2 in the outermost layer of the collective core 3, and the shield layer 5. The drain wire 7 is provided by being crushed so as to enter (be embedded in) the valley portion 8, and has a non-circular cross-sectional shape. The valley portion 8 is a region surrounded by the circumscribing circle of the collective core 3 and the outer peripheral surfaces of two electric wires 2 adjacent in the circumferential direction of the cable.

[0020] The drain wire 7 is provided in the same direction and at the same pitch as the stranding of the collective core 3, and is provided along the electric wire 2. After winding the tape member 4 around the collective core 3, the drain wire 7 is provided in the same direction and at the same pitch as the stranding of the collective core 3, so that the drain wire 7 and a part of the tape member 4 around it are arranged along the valley portion 8. Then, the shield layer 5 is provided, and the drain wire 7 is pushed inward in the cable radial direction by the shield layer 5, so that the drain wire 7 and the tape member 4 around it enter the valley portion 8. At this time, the drain wire 7 is crushed to become a non-circular shape (a shape along the valley portion 8 or a flattened shape), and the pushing of the drain wire 7 forms a recess 4a inward in the cable radial direction in the tape member 4. Furthermore, the sheath 6 is provided by extrusion, so that the drain wire 7 is further pushed inward in the cable radial direction by the sheath 6, so that the drain wire 7 enters the valley portion 8.

[0021] In order to make the drain wire 7 easily deformed when it is pressed radially inward into the shield layer 5 and the sheath 6 and to make it easy to enter the valley portion 8, it is preferable that the drain wire 7 is formed by stranding a plurality of strands 7a. In addition, in order to make the drain wire 7 easily deformed, it is preferable to use strands 7a that are relatively thin. More specifically, the outer diameter of the strands 7a 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 easily broken, 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 strands 7a are less likely to deform when it is pressed radially inward into the shield layer 5 and the sheath 6 and the drain wire 7 is less likely to enter the valley portion 8.

[0022] The number of the strands 7a constituting the drain wire 7 is preferably 7 or more and 45 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 wire 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 radially adjacent shield 5 is too small, which may increase the contact resistance. If the number of strands 7a constituting the drain wire 7 is more than 45, 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.

[0023] The twist pitch of the drain wire 7 is preferably 50 to 200 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 irregularities are likely to occur on the outer peripheral surface of the multi-core cable 1, whereas if the twist pitch exceeds 200 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.

[0024] (Sheath 6) The sheath 6 is provided so as to cover the periphery of the shield layer 5, and plays a role of 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) or fluororesin can be used. The thickness of the sheath 6 is preferably 0.8 mm or more and 2.0 mm or less. If the thickness of the sheath 6 is less than 0.8 mm, the extrusion amount (extrusion pressure) of the resin material constituting the sheath 6 becomes too small when the sheath 6 is formed by extrusion. Therefore, the drain wire 7 is difficult to be pushed inward in the cable radial direction. If the thickness of the sheath 6 exceeds 2.0 mm, the flexibility of the multi-core cable 1 may be deteriorated.

[0025] (Functions and Effects of the Embodiments) As described above, in the multi-core cable 1 according to this embodiment, the drain wire 7 is made of a twisted wire formed by twisting together a plurality of element wires 7a and is arranged in the same direction and at the same pitch as the twisting of the assembly core 3. The drain wire 7, together with a part of the tape member 4 surrounding the drain wire 7, is arranged so as to enter the valley portion 8 between circumferentially adjacent electric wires 2 in the outermost layer of the assembly core 3.

[0026] This prevents the outer circumferential surface of multi-core cable 1 from swelling up at the portion where drain wire 7 is provided, thereby suppressing deterioration of the appearance of multi-core cable 1. Furthermore, according to this embodiment, the outer circumferential surface of multi-core cable 1 becomes closer to a circular shape, eliminating the problem of multi-core cable 1 being difficult to bend in a specific direction, and realizing a multi-core cable 1 that is easy to wire. In other words, according to this embodiment, it is possible to realize a multi-core cable 1 that has a good appearance and is easy to wire.

[0027] (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.

[0028] [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); a drain wire (7) provided between the tape member (4) and the shielding layer (5); and a sheath (6) covering the periphery of the shielding layer (5), wherein the drain wire (7) is made of a twisted wire in which a plurality of element wires (7a) are twisted together and is provided in the same direction and at the same pitch as the twisting of the aggregate core (3), and the drain wire (7), together with a part of the tape member (4) around the drain wire (7), is provided so as to enter a valley portion (8) between adjacent electric wires (2) in the circumferential direction in the outermost layer of the aggregate core (3).

[0029] [2] The multi-core cable (1) described in [1], wherein the drain wire (7) is arranged so that its entirety enters the valley portion (8) and has a non-circular cross-sectional shape.

[0030] [3] The multi-core cable (1) according to [1] or [2], wherein the drain wire (7) is formed by stranding a plurality of strands (7a), and the outer diameter of the strands (7a) is 0.03 mm or more and 0.13 mm or less.

[0031] [4] The multi-core cable (1) according to any one of [1] to [3], wherein the wires (7a) constituting the drain wire (7) are made of copper or copper alloy wire, and the shielding layer (5) is made of aluminum or aluminum alloy wire.

[0032] [5] The multi-core cable (1) according to [4], wherein the wires (7a) constituting the drain wire (7) have a surface that is tin-plated.

[0033] (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]

[0034] 1...Multi-core cable 2...Electric wire 3. Collective core 4…Tape member 5…Shield layer 6…Sheath 7…Drain wire 7a…Element wire 8. Valley area

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 drain wire provided between the tape member and the shielding layer; a sheath covering the shield layer, The drain wire is made of a stranded wire formed by twisting a plurality of wires together, and is provided in the same direction and at the same pitch as the stranding of the collective core, the drain wire, together with a part of the tape member surrounding the drain wire, is provided so as to enter a valley portion between adjacent electric wires in the circumferential direction in the outermost layer of the collective core. Multicore cable.

2. the drain wire is provided so as to entirely enter the valley portion and has a non-circular cross-sectional shape; 2. The multi-conductor cable of claim 1.

3. The drain wire is configured by stranding a plurality of wires, The outer diameter of the wire is 0.03 mm or more and 0.13 mm or less.

2. The multi-conductor cable of claim 1.

4. The wire constituting the drain wire is made of copper or a copper alloy wire, The shield layer is made of aluminum or aluminum alloy wire.

2. The multi-conductor cable of claim 1.

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

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

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