Multi-core cable

Abstract

The invention provides a multi-core cable which is good in appearance and easy to wire. A multi-core cable (1) is provided with: an integrated core (3) in which a plurality of electric wires (2) are twisted; a tape member (4) which is spirally wound around the integrated 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); the drain wire (7) is composed of a twisted wire obtained by twisting a plurality of wire rods (7a), is provided at the same pitch in the same direction as the twisting of the integrated core (3), and is provided so as to enter, together with a part of the tape member (4) around the drain wire (7), an inter-valley portion (8) between the circumferentially adjacent electric wires (2) on the outermost layer of the integrated core (3).

Description

Technical Field

[0001] The invention relates to a multi-core cable. Background Art

[0002] It is known that there are multi-core cables in which a shielding layer is provided in a manner that covers a collective core formed by twisting a plurality of electric wires. In such a multi-core cable, in order to facilitate the grounding of the shielding layer (for example, connection to a ground electrode of a substrate), a drain wire electrically connected to the shielding layer is sometimes provided (for example, see Patent Documents 1 and 2).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2001-110250

[0006] Patent Document 2: Japanese Patent Application Publication No. 2009-245713 Summary of the invention

[0007] Problems to be solved by the invention

[0008] However, if a drain wire is provided, the outer peripheral surface of the portion where the drain wire is provided will bulge, causing a problem of deterioration in the appearance of the cable. In addition, since a portion of the outer peripheral surface of the cable bulges and the cross-sectional shape becomes a non-circular shape, it is difficult for the cable to bend in a specific direction, and sometimes it is difficult to route the cable.

[0009] Therefore, an object of the present invention is to provide a multi-core cable which has a good appearance and is easy to wire.

[0010] Methods for solving problems

[0011] The present invention aims to solve the above-mentioned problems and provides a multi-core cable, which comprises: a collective core formed by twisting a plurality of electric wires, a belt member spirally wound around the collective core, a shielding layer arranged in a manner covering the periphery of the belt member, a drain wire arranged between the belt member and the shielding layer, and a sheath covering the periphery of the shielding layer, the drain wire being composed of a stranded wire formed by twisting a plurality of wires and arranged in the same direction and at the same pitch as the twisting of the collective core, and the drain wire being arranged to enter the valley portion between the electric wires that are circumferentially adjacent and at the outermost layer of the collective core together with a portion of the belt member around the drain wire.

[0012] Effects of the Invention

[0013] According to the present invention, it is possible to provide a multi-core cable which has a good appearance and is easy to wire. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This 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.

[0015] Description of Reference Numerals

[0016] 1…multi-core cable, 2…electric wire, 3…collective core, 4…tape component, 5…shield, 6…sheath, 7…drain wire, 7a…wire material, 8…valley part. DETAILED DESCRIPTION

[0017] [Implementation Method]

[0018] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0019] Figure 1 1 is a cross-sectional view showing a cross section perpendicular to the longitudinal direction of the multi-core cable 1 of the present embodiment. The multi-core cable 1 is used as a cable for connecting electronic equipment and control devices, for example, for signal transmission and power supply.

[0020] like Figure 1 As shown, the multi-core cable 1 comprises a collective core 3 formed by twisting a plurality of electric wires 2, a belt member 4 spirally wound around the collective core 3, a shielding layer 5 arranged to cover the belt member 4, a sheath 6 covering the shielding layer 5, and a drain wire 7 arranged between the belt member 4 and the shielding layer 5.

[0021] (Wire 2)

[0022] The electric wire 2 is composed of an insulated electric wire, which has a conductor 21 composed of a stranded conductor formed by twisting a plurality of wires and an insulator 22 covering the conductor 21. The wire constituting the conductor 21 can be composed of copper or copper alloy wire. However, it is not limited to this, and the electric wire 2 can also be, for example, a coaxial wire further having a shielding layer and a sheath around the insulator 22. In addition, the electric wire 2 can be a twisted pair formed by twisting a pair of insulated electric wires, or a multi-core wire in which a plurality of insulated electric wires (or a plurality of conductors 21) are covered with a sheath. In the present embodiment, an electric wire 2 with an outer diameter of 0.6 mm or more is used. 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 circumferentially adjacent electric wires 2 becomes too small, and the configuration of the drain wire 7 to the valley portion 8 becomes difficult.

[0023] (Collection Core 3)

[0024] The core assembly 3 is formed by twisting a plurality of electric wires 2. Here, the core assembly 3 is formed by twisting four electric wires 2, but the number of electric wires 2 is not limited thereto. The core assembly 3 may also be formed by twisting a plurality of electric wires 2 in multiple layers. Figure 1, all the electric wires 2 constituting the collective core 3 are shown to have the same structure, but they may also include electric wires 2 of different structures. For example, the electric wires 2 may include twisted pair wires, coaxial wires, etc. in addition to insulated wires.

[0025] (Belt member 4)

[0026] The belt member 4 plays the role of maintaining the twist of the collective core 3 without unraveling, and is composed of a resin belt such as PET (polyethylene terephthalate), a paper belt, a non-woven fabric belt, etc. The belt member 4 is spirally wound around the collective core 3. The winding direction of the belt member 4 is the same direction as the twist direction of the collective core 3. Therefore, when the drain wire 7 is set, the belt member 4 can easily enter the valley part 8 between the wires 2 that are adjacent to each other in the circumferential direction and in the outermost layer of the collective core 3. In addition, the winding direction of the belt member 4 is the direction in which the belt member 4 rotates from the other end to the one end when viewed from one end of the multi-core cable 1. In addition, the twist direction of the collective core 3 is the direction in which the wires 2 rotate from the other end to the one end when viewed from one end of the multi-core cable 1.

[0027] In addition, it is desired that the winding pitch of the tape member 4 is substantially the same as the twisting pitch of the core assembly 3, preferably 0.8 times or more and 1.2 times or less of the twisting pitch of the core assembly 3. More preferably, the winding pitch of the tape member 4 is equal to the twisting pitch of the core assembly 3. Thus, by winding the tape member 4 along the electric wire 2, the tape member 4 can more easily enter the valley portion 8. It should be noted that the winding pitch of the tape member 4 refers to the interval along the length direction of the cable where the tape member 4 is at the same position in the circumferential direction of the cable. Similarly, the twisting pitch of the core assembly 3 refers to the interval along the length direction of the cable where any electric wire 2 is at the same position in the circumferential direction of the cable. In addition, the thickness of the tape member 4 is preferably 12 μm or more and 100 μm or less. When the thickness of the tape member 4 is less than 12 μm, the tape member 4 may be broken due to the drain wire 7. When the thickness of the tape member 4 exceeds 100 μm, it is difficult for the tape member 4 to enter the valley portion 8.

[0028] (Shielding layer 5)

[0029] The shielding layer 5 is provided so as to cover the periphery of the belt member 4. The shielding layer 5 is formed, for example, using a plurality of metal wires. In the present embodiment, the shielding layer 5 is formed by a braided shielding member formed by braiding a plurality of metal wires. However, not limited thereto, the shielding layer 5 may also be a transversely wound shielding member in which a plurality of metal wires are wound in a spiral shape. In the present embodiment, a braided shielding member using aluminum or aluminum alloy wires as the metal wire is used as the shielding layer 5. Thus, the multi-core cable 1 can be made lightweight. In addition, the shielding layer 5 may also be formed by interweaving a first wire and a second wire, for example, wherein the first wire is formed by aluminum or aluminum alloy wire, and the second wire is formed by copper or copper alloy wire or copper foil wire.

[0030] (Drain wire 7)

[0031] The drain wire 7 is used to ground the shield layer 5, and is provided in direct contact with the shield layer 5 and electrically connected to the shield layer 5. The shield layer 5 is grounded via the drain wire 7 by connecting the drain wire 7 to, for example, a ground electrode of the substrate. In the present embodiment, the drain wire 7 is provided between the belt member 4 and the shield layer 5.

[0032] The drain wire 7 is composed of a stranded wire formed by twisting a plurality of wires 7a. In order to facilitate soldering connection to a substrate or the like, the wire 7a constituting the drain wire 7 may be composed of copper or copper alloy wire. In addition, when aluminum or aluminum alloy wire is used in the shield layer 5 for weight reduction, the surface of the wire 7a may be tinned to suppress galvanic corrosion.

[0033] In the multi-core cable 1 of the present embodiment, the drain wire 7 is arranged to enter the valley portion (recessed portion) 8 between the outermost layer of the collective core 3 and the circumferentially adjacent electric wires 2 together with a portion of the belt member 4 surrounding the drain wire 7. That is, the drain wire 7 is arranged in an area surrounded by a portion of the belt member 4 and the shielding layer 5, and the portion of the belt member 4 is a portion arranged to enter the valley portion 8 between the outermost layer of the collective core 3 and the circumferentially adjacent electric wires 2. The drain wire 7 is arranged to be flattened in a manner of entering (burying) the valley portion 8, and its cross-sectional shape is a non-circular shape. It should be noted that the valley portion 8 is an area surrounded by the circumscribed circle of the collective core 3 and the outer peripheral surface of two electric wires 2 adjacent to each other in the circumferential direction of the cable.

[0034] The drain wire 7 is arranged in the same direction and at the same pitch as the twisting of the collective core 3, and is arranged along the electric wire 2. After the tape member 4 is wound around the collective core 3, the drain wire 7 is arranged in the same direction and at the same pitch as the twisting 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, by providing the shielding layer 5, the drain wire 7 is pressed inwardly in the radial direction of the cable by the shielding layer 5, and the drain wire 7 and the tape member 4 around it enter the valley portion 8. At this time, the drain wire 7 is flattened to a non-circular shape (a shape along the valley portion 8 or a flat shape), and a recess 4a that is recessed inwardly in the radial direction of the cable is formed in the tape member 4 by the pressing of the drain wire 7. Furthermore, the sheath 6 is provided thereafter by extrusion, thereby the drain wire 7 is further pressed inwardly in the radial direction of the cable by the sheath 6, and the drain wire 7 enters the valley portion 8.

[0035] When the drain wire 7 is pressed radially inwardly toward the shielding layer 5 and the sheath 6, the drain wire 7 is easily deformed. In order to easily enter the valley portion 8, the drain wire 7 is preferably composed of a plurality of wires 7a that are twisted together. In addition, in order to facilitate the deformation of the drain wire 7, it is preferred to use a relatively thin wire as the wire 7a. More specifically, the outer diameter of the wire 7a can be greater than 0.03 mm and less than 0.13 mm. In addition, if the outer diameter of the wire 7a is less than 0.03 mm, the wire 7a is prone to breakage. In addition, in order to ensure the conductor cross-sectional area, more wires 7a need to be used, which increases the cost. In addition, if the outer diameter of the wire 7a is greater than 0.13 mm, it is not easy to deform when pressed radially inwardly toward the shielding layer 5 and the sheath 6, and the drain wire 7 is difficult to enter the valley portion 8.

[0036] The number of wires 7a constituting the drain wire 7 is preferably 7 or more and 45 or less. This is because if the number of wires 7a constituting the drain wire 7 is less than 7, the drain wire 7 is difficult to be flattened, and unevenness is likely to occur on the outer peripheral surface of the multi-core cable 1, and it is difficult to solder (that is, the wires 7a that are not wetted by the solder are generated, the connection reliability is reduced, or the ability to resist tension (external forces such as stretching and bending) is weakened). In addition, if the number of wires 7a constituting the drain wire 7 is less than 7, the number of wires 7a in contact with the shielding layer 5 adjacent in the radial direction is too small, and the contact resistance may become high. If the number of wires 7a constituting the drain wire 7 is more than 45, the twisting of the drain wire 7 is likely to be disordered (the wires 7a are likely to float), and the cost becomes high.

[0037] In addition, the twist pitch of the drain wire 7 is preferably more than 50 times and less than 200 times the outer diameter of the wire 7a constituting the drain wire 7. This is because if the twist pitch of the drain wire 7 is less than 50 times the outer diameter of the wire 7a, the drain wire 7 is not easily flattened, and the outer peripheral surface of the multi-core cable 1 is prone to unevenness. If it exceeds 200 times, the wire 7a is easy to spread out, and the soldering operation becomes difficult. It should be noted that the twist pitch of the drain wire 7 refers to the interval along the length direction of the drain wire where any wire 7a is in the same position in the circumferential direction of the drain wire 7.

[0038] (Sheath 6)

[0039] The sheath 6 is provided so as to cover the periphery of the shielding layer 5, and plays a role in protecting the collective core 3 and the shielding layer 5. The material of the sheath 6 is not particularly limited, and for example, PVC (polyvinyl chloride), fluororesin, etc. may be used. The thickness of the sheath 6 is preferably greater than 0.8 mm and less than 2.0 mm. If the thickness of the sheath 6 is less than 0.8 mm, when the sheath 6 is formed by extrusion, the extrusion amount (extrusion pressure) of the resin material constituting the sheath 6 becomes too small. Therefore, it is difficult for the drain wire 7 to be pressed radially inwardly of the cable. In addition, if the thickness of the sheath 6 exceeds 2.0 mm, the flexibility of the multi-core cable 1 may deteriorate.

[0040] (Functions and Effects of Implementation Methods)

[0041] As described above, in the multi-core cable 1 of the present embodiment, the drain wire 7 is composed of a stranded wire formed by twisting a plurality of wires 7a, and is arranged in the same direction and at the same spacing as the twisting of the collective core 3, and the drain wire 7 is arranged to enter the valley portion 8 between the wires 2 that are adjacent in the circumferential direction and in the outermost layer of the collective core 3 together with a portion of the belt member 4 surrounding the drain wire 7.

[0042] Thus, the outer peripheral surface of the multi-core cable 1 is suppressed from bulging in the portion where the drain wire 7 is provided, and the deterioration of the appearance of the multi-core cable 1 can be suppressed. In addition, according to the present embodiment, the outer peripheral surface of the multi-core cable 1 is close to a circular shape, so that the disadvantage that the multi-core cable 1 is difficult to bend in a specific direction is eliminated, and the multi-core cable 1 that is easy to wire can be realized. That is, according to the present embodiment, a multi-core cable 1 with a good appearance and easy wiring can be realized.

[0043] (Summary of Implementation Methods)

[0044] Next, the technical ideas grasped from the above-described embodiments are described by referring to the reference numerals in the embodiments. However, the reference numerals in the following description do not limit the constituent elements in the claims to the members specifically shown in the embodiments.

[0045] [1] A multi-core cable (1), comprising an aggregate core (3) formed by twisting a plurality of electric wires (2), a belt member (4) spirally wound around the aggregate core (3), a shielding layer (5) arranged to cover the periphery of the belt member (4), a drain wire (7) arranged between the belt 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 composed of a stranded wire formed by twisting a plurality of wires (7a) and is arranged in the same direction and at the same pitch as the twisting of the aggregate core (3), and the drain wire (7) is arranged to enter, together with a portion of the belt member (4) around the drain wire (7), a valley portion (8) between the electric wires (2) which are adjacent to each other in the circumferential direction and are located at the outermost layer of the aggregate core (3).

[0046] [2] The multi-core cable (1) according to [1], wherein the drain wire (7) is arranged so that its entirety enters the valley portion (8), and its cross-sectional shape is a non-circular shape.

[0047] [3] The multi-core cable (1) according to [1] or [2], wherein the drain wire (7) is formed by twisting a plurality of wires (7a) together, and the outer diameter of the wire (7a) is greater than or equal to 0.03 mm and less than or equal to 0.13 mm.

[0048] [4] A multi-core cable (1) according to any one of [1] to [3], wherein the wire (7a) constituting the drain wire (7) is made of copper or copper alloy wire, and the shielding layer (5) is made of aluminum or aluminum alloy wire.

[0049] [5] The multi-core cable (1) according to [4], wherein the wire material (7a) constituting the drain wire (7) is tinned on its surface.

[0050] (Note)

[0051] The embodiments of the present invention are described above, but the embodiments described above do not limit the invention involved in the claims. In addition, it should be noted that all combinations of features described in the embodiments are not limited to the means necessary for solving the problems of the invention. In addition, the present invention can be implemented by appropriately deforming within the scope of its main purpose.

Claims

1. A multi-core cable, comprising: The core is made of multiple wires twisted together. a belt member spirally wound around the collective core, a shielding layer provided so as to cover the periphery of the belt member, a drain wire disposed between the tape member and the shielding layer, and A sheath covering the periphery of the shielding layer; The drain wire is composed of a stranded wire formed by twisting a plurality of wires, and is arranged in the same direction and at the same pitch as the twisting of the collective core. The drain wire is provided so as to enter a valley portion between the electric wires which are located in the outermost layer of the collective core and are adjacent in the circumferential direction together with a portion of the tape member around the drain wire.

2. The multi-core cable according to claim 1, wherein: The drain wire is disposed so that its entirety enters the valley portion and its cross-sectional shape is a non-circular shape.

3. The multi-core cable according to claim 1, wherein: The drain wire is formed by twisting a plurality of wires together. The outer diameter of the wire is greater than or equal to 0.03 mm and less than or equal to 0.13 mm.

4. The multi-core cable according to claim 1, wherein: The wire material constituting the drain wire is composed of copper or copper alloy wire, The shielding layer is formed by using aluminum or aluminum alloy wire.

5. The multi-core cable according to claim 4, wherein: The surface of the wire material constituting the drain wire is plated with tin.

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