Multi-core cable

Abstract

The present disclosure provides a multi-core cable having bending resistance and oil resistance. A multi-core cable is provided with: an oil-absorbent filler; and a core disposed so as to surround the oil-absorbent filler, the core being formed by twisting a plurality of electric wires, the core having a plurality of layers in which the plurality of electric wires are arranged on the circumference in a cross-section perpendicular to the longitudinal direction of the core, the innermost layer of the layers being closest to the oil-absorbent filler, and the innermost layer of the layers being closest to the oil-absorbent filler. The twist pitch of the electric wires in the innermost layer is equal to or greater than 0.45 times the twist pitch of the electric wires in the outermost layer of the layers and less than 0.8 times the twist pitch of the electric wires in the outermost layer of the layers.

Description

Technical Field

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

[0002] Patent document 1 discloses a core wire for a multi-core cable, comprising: a conductor formed by twisting a plurality of wires; a first insulating film covering the outer periphery of the conductor and comprising a polyethylene resin; and a second insulating film disposed in contact with the outer periphery of the first insulating film and comprising a copolymer of ethylene and an alpha olefin having a carbonyl group.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2022-040960

[0006] Multi-core cables used in factories and the like are sometimes arranged in drive units and the like. In addition, oil and the like may sometimes adhere to the multi-core cables in factories and the like. Therefore, multi-core cables used in factories and the like are required to have bending resistance and oil resistance. Summary of the invention

[0007] Therefore, an object of the present disclosure is to provide a multi-core cable having bending resistance and oil resistance.

[0008] The multi-core cable disclosed herein comprises: an oil-absorbing filler; and a core configured to surround the oil-absorbing filler, wherein the core is formed by twisting a plurality of wires, and in a cross section of the core perpendicular to the length direction, the core has a plurality of layers of the plurality of wires arranged circumferentially, the innermost layer of the layers being closest to the oil-absorbing filler, and the lay length of the wires in the innermost layer being greater than or equal to 0.45 times the lay length of the wires in the outermost layer of the layers and less than 0.8 times the lay length of the wires in the outermost layer of the layers.

[0009] Effects of the Invention

[0010] According to the present disclosure, a multi-core cable having bending resistance and oil resistance can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a cross-sectional view of a multi-core cable according to one embodiment of the present disclosure, taken on a plane perpendicular to the longitudinal direction.

[0012] Figure 2 This is a cross-sectional view of a multi-core cable according to another embodiment of the present disclosure, taken on a plane perpendicular to the longitudinal direction.

[0013] Figure 3 This is a cross-sectional view of a multi-core cable according to another embodiment of the present disclosure, taken on a plane perpendicular to the longitudinal direction.

[0014] Figure 4 This is a diagram for explaining the evaluation method of bending resistance.

[0015] Description of Reference Numerals

[0016] 10: Multi-core cable;

[0017] 20: Multi-core cable;

[0018] 30: Multi-core cable;

[0019] 11: Oil-absorbing filler;

[0020] 12: Wires;

[0021] 12A: First wire;

[0022] 12B: Second wire;

[0023] 12C: Third wire;

[0024] 121: Conductor;

[0025] 121A: first conductor;

[0026] 121B: second conductor;

[0027] 121C: third conductor;

[0028] 122: Insulator;

[0029] 122A: first insulator;

[0030] 122B: second insulator;

[0031] 122C: third insulator;

[0032] 32: twisted pair wire;

[0033] 13: core;

[0034] 33: core;

[0035] 131: innermost layer (layer);

[0036] 132: middle layer (layer);

[0037] 133: Outermost layer (layer);

[0038] 134: Gap;

[0039] 14: Pressing layer;

[0040] 15: skin;

[0041] 16: Metal shielding layer;

[0042] C1: circle;

[0043] C2: circle;

[0044] C3: circle;

[0045] C4: circle;

[0046] 40: Multi-core cable;

[0047] 411: first spindle;

[0048] 412: second spindle;

[0049] 42: Hollow arrow. DETAILED DESCRIPTION

[0050] Hereinafter, specific implementation methods will be described.

[0051] [Description of Embodiments of the Present Disclosure]

[0052] First, the embodiments of the present disclosure will be described by way of example. In the following description, the same or corresponding elements are denoted by the same reference numerals, and the same description thereof will not be repeated.

[0053] (1) A multi-core cable according to one embodiment of the present invention comprises: an oil-absorbing filler; and a core configured to surround the oil-absorbing filler, wherein the core is formed by twisting a plurality of wires, wherein in a cross section of the core perpendicular to a longitudinal direction, the core has a plurality of layers of the plurality of wires arranged circumferentially, the innermost layer of the layers being closest to the oil-absorbing filler, and the lay length of the wires in the innermost layer is greater than or equal to 0.45 times the lay length of the wires in the outermost layer of the layers and less than 0.8 times the lay length of the wires in the outermost layer of the layers.

[0054] A multi-core cable of one embodiment of the present disclosure has an oil-absorbing filler, which can absorb oil that adheres to the multi-core cable and intrudes into the interior. Therefore, even if oil intrudes into the interior of the multi-core cable, the insulation resistance of the wires of the multi-core cable can be suppressed from decreasing, and the oil resistance can be improved.

[0055] By setting the twist length of the wires in the innermost layer to be equal to or greater than 0.45 times the twist length of the wires in the outermost layer, sufficient gaps can be formed between the wires in the innermost layer for oil to easily penetrate. Therefore, the oil reaching the innermost layer can be easily absorbed by the oil-absorbing filler, thereby improving the oil resistance of the multi-core cable.

[0056] Furthermore, by setting the twist pitch of the electric wires in the innermost layer to be smaller than 0.8 times the twist pitch of the electric wires in the outermost layer, the bending resistance of the multi-core cable can be improved.

[0057] (2) In the above (1), the electric wire may include a conductor and an insulator covering the conductor, and the insulator may contain a resin material containing polyvinyl chloride or polyolefin as a main component.

[0058] As a resin material, the insulator contains polyvinyl chloride or polyolefin as a main component, thereby improving the flexibility of the electric wire and the multi-core cable including the electric wire, and can suppress the cost compared with the case where fluororesin or the like is used as the resin material. By improving the flexibility of the electric wire and the multi-core cable, the bending resistance of the multi-core cable is also improved.

[0059] (3) In the above (1) or (2), the core may include three or more layers formed of the electric wires, and the lay length of the electric wires in an intermediate layer adjacent to the outermost layer and arranged closer to the oil-absorbing filler than the outermost layer is greater than or equal to 0.7 times the lay length of the electric wires in the outermost layer and less than 0.95 times the lay length of the electric wires in the outermost layer.

[0060] By setting the lay length of the wires in the middle layer to be equal to or greater than 0.7 times the lay length of the wires in the outermost layer, sufficient gaps can be formed between the wires in the middle layer for oil to easily penetrate. Therefore, the oil reaching the middle layer can be further penetrated into the core, and the oil can be easily absorbed by the oil-absorbing filler, thereby improving the oil resistance of the multi-core cable.

[0061] Furthermore, by setting the twist pitch of the electric wires in the middle layer to be smaller than 0.95 times the twist pitch of the electric wires in the outermost layer, the bending resistance of the multi-core cable can be improved.

[0062] (4) In any one of the above (1) to (3), the multi-core cable may further include a sheath covering the cores, wherein the sheath contains a resin material having polyvinyl chloride or polyolefin as a main component.

[0063] The multi-core cable has an outer sheath to protect the electric wires included in the cores arranged inside the outer sheath, thereby improving durability.

[0064] As a resin material, the outer sheath contains polyvinyl chloride or polyolefin as a main component, thereby improving the flexibility of the multi-core cable and suppressing the cost compared with the case where fluororesin or the like is used as the resin material. By improving the flexibility of the multi-core cable, the bending resistance of the multi-core cable is also improved.

[0065] (5) In the above (4), a rolled layer may be provided between the core and the outer skin, and the rolled layer may include an oil-absorbing tape.

[0066] By disposing the crimping layer between the core and the outer sheath, the core and the outer sheath can be prevented from directly contacting each other. Therefore, when the electric wire is to be taken out at the end in the longitudinal direction of the multi-core cable, the outer sheath can be easily peeled off.

[0067] The crimping layer includes an oil-absorbing tape, which can prevent the oil that has entered the multi-core cable from further entering the inside and contacting the wires. Therefore, it is possible to prevent the insulation resistance of the wires of the multi-core cable from decreasing, and improve oil resistance.

[0068] (6) In the above (5), a metal shield layer may be further provided between the outer skin and the crimped layer.

[0069] The multi-core cable has a metal shielding layer, which can improve the bending resistance of the multi-core cable, and can suppress signal leakage to the outside and the intrusion of radio waves from the outside. In addition, the multi-core cable has a metal shielding layer, which can shield heat from the outside and protect the core from the influence of external heat. Moreover, the multi-core cable has a metal shielding layer, which can mechanically protect the core even if the outer skin is damaged.

[0070] [Details of the embodiments of the present disclosure]

[0071] Hereinafter, a specific example of a multi-core cable of an embodiment of the present disclosure (hereinafter referred to as "this embodiment") is described with reference to the accompanying drawings. It should be noted that the present invention is not limited to these examples, but is shown by the claims, and is intended to include all changes within the meaning and scope equivalent to the claims.

[0072] [Multi-core cable]

[0073] Figure 1 Schematic diagram of a cross section perpendicular to the longitudinal direction of the multi-core cable of the present embodiment is shown in FIG. Figure 2 , Figure 3 A schematic diagram of a cross section perpendicular to the longitudinal direction of a multi-core cable of another configuration example of the present embodiment is shown in FIG. Figure 1 , Figure 2 , Figure 3 In the diagram, the length direction of the multi-core cable refers to the Z axis, that is, the direction along the axis perpendicular to the paper. Figure 1 , Figure 2 , Figure 3 , a cross section on the XY plane perpendicular to the Z axis is shown.

[0074] Figure 2 , Figure 3 This is an explanatory diagram of another configuration example of the multi-core cable of this embodiment, and therefore mainly uses Figure 1 To illustrate, use Figure 2 , Figure 3 To explain.

[0075] like Figure 1 As shown, the multi-core cable 10 of the present embodiment may include: an oil-absorbing filler 11; and a core 13 disposed so as to surround the oil-absorbing filler 11, the core 13 being formed by twisting a plurality of electric wires 12.

[0076] (1) About the components of multi-core cables

[0077] Each member included in the multi-core cable of this embodiment will be described.

[0078] (1-1) Oil-absorbing fillers

[0079] The multi-core cable 10 of the present embodiment may include an oil-absorbing filler 11. The oil-absorbing filler 11 is a filler capable of absorbing oil, and refers to a filler capable of absorbing oil ten times or more of its own weight when immersed in oil.

[0080] The material of the oil-absorbing filler 11 is not particularly limited, but the oil-absorbing filler 11 may include one or more fibers selected from staple fibers, cotton, kapok fibers, and the like.

[0081] The oil-absorbing filler 11 may be disposed so as to be surrounded by the core 13, and may be disposed in the gap 134 of the core 13. The gap 134 in which the oil-absorbing filler 11 is disposed may be disposed inside the core 13 formed by twisting a plurality of electric wires 12, for example. Figure 1 As shown, in a cross section of the core 13 perpendicular to the longitudinal direction, the core 13 may be arranged in a central region including the center of the core 13 .

[0082] The multi-core cable of this embodiment has an oil-absorbing filler 11, and the oil-absorbing filler 11 can absorb the oil that adheres to the multi-core cable 10 and intrudes into the inside. Therefore, even if oil intrudes into the inside of the multi-core cable 10, the insulation resistance of the electric wire 12 of the multi-core cable 10 can be suppressed from decreasing, and the oil resistance can be improved.

[0083] In this specification, oil resistance refers to a property that can suppress a decrease in insulation resistance when the multi-core cable 10 is immersed in oil.

[0084] (1-2)core

[0085] The core 13 has a structure in which a plurality of electric wires 12 are twisted. In a cross section perpendicular to the longitudinal direction of the core 13, the core 13 has a structure in which the electric wires 12 are arranged and twisted in a manner to have a plurality of layers in which the electric wires 12 are arranged on the circumference. The core 13 includes an innermost layer 131 which is closest to the oil-absorbing filler 11 and an outermost layer 133 which is farthest from the oil-absorbing filler 11 and includes the outer surface of the core 13. The core 13 may have a plurality of layers of two or more layers formed of the electric wires 12.

[0086] The configuration having a plurality of layers of a plurality of wires 12 arranged on a circumference refers to the configuration in the following manner: Figure 1 As shown, in a cross section of the core 13 perpendicular to the longitudinal direction, the layers in which the electric wires 12 are arranged along the circumference of a circle form a plurality of layers along the diameter of the circle. Figure 1 The core 13 of the multi-core cable 10 shown has three layers, namely, an innermost layer 131, an intermediate layer 132, and an outermost layer 133. The innermost layer 131 has a structure in which the electric wires 12 are arranged between the circles C1 and C2 along the circumference. The intermediate layer 132 has a structure in which the electric wires 12 are arranged between the circles C2 and C3 along the circumference. The outermost layer 133 has a structure in which the electric wires 12 are arranged between the circles C3 and C4 along the circumference.

[0087] Furthermore, the lay pitch PI of the wires 12 in the innermost layer 131 is preferably greater than or equal to 0.45 times the lay pitch PO of the wires 12 in the outermost layer 133 and less than 0.8 times the lay pitch PO of the wires 12 in the outermost layer 133. That is, PI÷PO is preferably greater than or equal to 0.45 and less than 0.8.

[0088] The lay length refers to the length of the electric wire 12 constituting the core 13 as the stranded wire when it is twisted once. This length refers to the length along the central axis of the stranded wire. The lay length can be measured in accordance with JIS C 3005 (2014).

[0089] When measuring the twist length of the electric wires 12 in the innermost layer 131 or the intermediate layer 132 , the measurement may be performed after removing the electric wires 12 of other layers covering the layer to be measured so that the layer to be measured is exposed.

[0090] By setting the twist pitch PI of the electric wires 12 in the innermost layer 131 to be equal to or greater than 0.45 times the twist pitch PO of the electric wires 12 in the outermost layer 133, sufficient gaps for oil to easily penetrate can be formed between the electric wires 12 in the innermost layer 131. Therefore, the oil reaching the innermost layer 131 can be easily absorbed by the oil-absorbing filler 11, thereby improving the oil resistance of the multi-core cable 10.

[0091] Furthermore, by setting the twist pitch PI of the electric wires 12 in the innermost layer 131 to be smaller than 0.8 times the twist pitch PO of the electric wires 12 in the outermost layer 133 , the bending resistance of the multi-core cable 10 can be improved.

[0092] like Figure 1 As shown, the core 13 may further include an intermediate layer 132 in addition to the innermost layer 131 and the outermost layer 133, and may include three or more layers formed by the electric wires 12. It should be noted that the core 13 may include a plurality of layers as the intermediate layer 132.

[0093] In the core 13, the lay pitch PM of the electric wire 12 in the intermediate layer 132 adjacent to the outermost layer 133 and arranged closer to the oil-absorbing filler 11 than the outermost layer 133 is preferably greater than or equal to 0.7 times the lay pitch PO of the electric wire 12 in the outermost layer 133 and less than 0.95 times the lay pitch PO of the electric wire 12 in the outermost layer 133. That is, PM÷PO is preferably greater than or equal to 0.7 and less than 0.95.

[0094] By setting the twist pitch PM of the electric wires 12 in the middle layer 132 to be equal to or greater than 0.7 times the twist pitch PO of the electric wires 12 in the outermost layer 133, sufficient gaps for oil to easily penetrate can be formed between the electric wires 12 in the middle layer 132. Therefore, the oil reaching the middle layer 132 can be further penetrated into the core 13, and the oil can be easily absorbed by the oil-absorbing filler 11, so that the oil resistance of the multi-core cable 10 can be improved.

[0095] Furthermore, by setting the twist pitch PM of the electric wires 12 in the intermediate layer 132 to be smaller than 0.95 times the twist pitch PO of the electric wires 12 in the outermost layer 133 , the bending resistance of the multi-core cable 10 can be improved.

[0096] (1-2-1) Wires

[0097] The electric wire 12 included in the core 13 of the multi-core cable of the present embodiment may include a conductor 121 and an insulator 122 covering the conductor 121. Therefore, the conductor 121 and the insulator 122 will be described.

[0098] (A) Conductor

[0099] The conductor 121 may be a single conductor wire or a plurality of conductor wires. When the conductor 121 has a plurality of conductor wires, the plurality of conductor wires may be twisted in advance. That is, when the conductor 121 has a plurality of conductor wires, the conductor 121 may be a twisted wire of the plurality of conductor wires.

[0100] The material of the conductor 121 is not particularly limited, but for example, one or more conductor materials selected from copper alloy, copper, silver-plated annealed copper, and tin-plated annealed copper can be used. As copper, annealed copper can be preferably used.

[0101] The cross-sectional area of ​​the conductor 121 is not particularly limited, but for example, the cross-sectional area is preferably equal to or greater than 0.05 mm. 2 And less than or equal to 3mm 2 .

[0102] (B) Insulator

[0103] like Figure 1As shown, the insulator 122 may cover the outer surface of the conductor 121, specifically, the outer surface along the length direction of the electric wire 12. The insulator 122 may include a resin material described below.

[0104] (Resin material)

[0105] The insulator 122 may include a resin material. The resin material is not particularly limited, but preferably contains polyvinyl chloride or polyolefin as a main component, for example. The main component refers to the component that is contained in the largest amount by mass in the resin material.

[0106] As a resin material, the insulator 122 contains polyvinyl chloride or polyolefin as a main component, thereby improving the flexibility of the electric wire 12 and the multi-core cable 10 including the electric wire 12, and can suppress costs compared to the case where fluororesin or the like is used as the resin material. By improving the flexibility of the electric wire 12 and the multi-core cable 10, the bending resistance of the multi-core cable 10 is also improved.

[0107] The polyolefin is not particularly limited. Examples of the polyolefin include polyethylene (PE), ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer (EEA), and other ethylene acrylate copolymers, ethylene α-olefin copolymers, ethylene methyl acrylate copolymers, ethylene butyl acrylate copolymers, ethylene methyl methacrylate copolymers, ethylene acrylic acid copolymers, partially saponified EVA, maleic anhydride-modified polyolefins, and ethylene acrylate maleic anhydride copolymers. These resins may be used alone or in combination of two or more.

[0108] The resin material may or may not be cross-linked.

[0109] However, when the resin material is cross-linked, the heat resistance, strength, and corrosion resistance of the electric wire 12 can be improved. Therefore, when the electric wire 12 is used for applications requiring heat resistance, strength, and corrosion resistance, it is preferable that the resin material is cross-linked.

[0110] (additive)

[0111] In addition to the above-mentioned resin material, the insulator 122 may contain additives such as a flame retardant, a flame retardant auxiliary, an antioxidant, a lubricant, a colorant, a reflection imparting agent, a masking agent, a processing stabilizer, and a plasticizer.

[0112] (1-2-2) Regarding the structure of electric wires

[0113] The structure of the electric wire 12 of the core 13 of the multi-core cable of this embodiment is not particularly limited. Figure 1 , Figure 2 As in the multi-core cables 10 and 20 shown in the drawings, the core 13 is constituted by a plurality of electric wires 12 having the same size and other structures.

[0114] In addition, you can Figure 3 As in the multi-core cable 30 shown, the core 33 is constituted by the first electric wire 12A, the second electric wire 12B, and the third electric wire 12C having different structures such as sizes.

[0115] exist Figure 3 In the multi-core cable 30 shown, the first electric wire 12A has a first conductor 121A and a first insulator 122A, the second electric wire 12B has a second conductor 121B and a second insulator 122B, and the third electric wire 12C has a third conductor 121C and a third insulator 122C. The preferred configurations of the conductors and insulators have been described above, so the description thereof is omitted.

[0116] You can also Figure 3 As shown in the multi-core cable 30, two first electric wires 12A are twisted together to form a twisted pair of electric wires 32, and then twisted together with other electric wires 12 to form a core 33. Figure 3 Although an example in which the twisted pair electric wire 32 is formed using the first electric wire 12A is shown, the twisted pair electric wire may be formed using the second electric wire 12B and the third electric wire 12C.

[0117] (1-3) Skin

[0118] like Figure 1 As shown, the multi-core cable 10 may further include a sheath 15 covering the core 13 .

[0119] The multi-core cable 10 has the outer sheath 15 to protect the electric wires 12 included in the cores 13 disposed inside, thereby improving durability.

[0120] (Resin material)

[0121] The outer sheath 15 may include a resin material. The resin material is not particularly limited, but preferably contains polyvinyl chloride or polyolefin as a main component, and more preferably contains polyolefin as a main component. The definition of the main component and the polyolefin that can be preferably used have been described in the section on the insulator 122 of the electric wire 12, so the description is omitted.

[0122] As a resin material, the outer sheath 15 contains polyvinyl chloride or polyolefin as a main component, thereby improving the flexibility of the multi-core cable 10 and suppressing the cost compared with the case where fluororesin or the like is used as the resin material. By improving the flexibility of the multi-core cable 10, the bending resistance of the multi-core cable 10 is also improved.

[0123] The resin material may or may not be cross-linked.

[0124] However, when the resin material is cross-linked, the heat resistance, strength, and corrosion resistance of the multi-core cable 10 can be improved. Therefore, when the multi-core cable 10 is used for applications requiring heat resistance, strength, and corrosion resistance, it is preferable that the resin material is cross-linked.

[0125] (additive)

[0126] The outer cover 15 may contain additives such as a flame retardant, a flame retardant auxiliary, an antioxidant, a lubricant, a colorant, a reflection imparting agent, a masking agent, a processing stabilizer, and a plasticizer in addition to the above-mentioned resin material.

[0127] (1-4) Pressing layer

[0128] The multi-core cable 10 of this embodiment may also have a compression layer 14 between the core 13 and the outer sheath 15. The compression layer 14 may be a tape made of an insulating material such as paper, nonwoven fabric, or polyester resin, which is spirally wound around the outer circumference of the core 13 along the longitudinal direction of the core 13.

[0129] By disposing the crimping layer 14 between the core 13 and the sheath 15, it is possible to prevent the core 13 from directly contacting the sheath 15. Therefore, when the electric wires 12 are to be taken out at the end in the longitudinal direction of the multi-core cable 10, the sheath 15 can be easily peeled off.

[0130] In addition, the crimping layer 14 may include an oil-absorbing tape. By including the oil-absorbing tape in the crimping layer 14, the oil that has entered the multi-core cable 10 can be prevented from further entering the interior and contacting the electric wires 12. Therefore, the insulation resistance of the electric wires 12 of the multi-core cable 10 can be prevented from being reduced, and the oil resistance can be improved.

[0131] The oil-absorbing tape is a tape that can absorb oil ten times or more of its own weight when immersed in oil.

[0132] When the tape is wound around the outer periphery of the core 13 to form the rolled layer 14 as described above, the winding direction of the tape can be arbitrarily selected, for example, it can be the same direction as the twisting direction of the core 13 already described, or it can be a direction different from the twisting direction of the core 13.

[0133] (1-5) Metal shielding layer

[0134] like Figure 2 The multi-core cable 20 shown, Figure 3 Like the multi-core cable 30 shown in the figure, the multi-core cable of this embodiment may further include a metal shield layer 16 between the outer sheath 15 and the crimping layer 14 .

[0135] The metal shielding layer 16 may include a conductive material.

[0136] For example, the metal shield layer 16 may be formed by spirally winding a conductive tape including a conductive layer along the length direction of the core 13 .

[0137] In this case, the conductive tape may be composed of only a conductive layer, or may be configured such that the conductive layer is disposed on one or more surfaces selected from the upper surface and the lower surface of the base member.

[0138] The material of the conductive layer is not particularly limited, but preferably contains metal, and for example, metal foil can be used. When the conductive layer contains metal, the material of the metal is not particularly limited, and for example, copper, copper alloy, aluminum, aluminum alloy, etc. can be used.

[0139] The material of the base member is not particularly limited, but is preferably made of an insulating material such as an organic polymer material or a nonwoven fabric. Examples of the organic polymer material include polyester resins such as polyethylene terephthalate (PET), polyolefin resins such as polypropylene, and vinyl resins such as polyvinyl chloride. The base member may be a base member including an insulating material or a base member consisting only of an insulating material.

[0140] When the metal shield layer 16 is formed by winding a conductive tape as described above, the winding direction of the conductive tape can be arbitrarily selected, for example, the same direction as the twisting direction of the core 13 or a direction different from the twisting direction of the core 13 .

[0141] The metal shield layer 16 may be formed of a metal wire. In this case, the metal shield layer 16 may be formed by arranging the metal wire into any one structure selected from a braided structure and a transversely wound structure.

[0142] Copper, aluminum, copper alloy, etc. can be used as the material of the metal wire. The surface of the metal wire can also be plated with silver or tin. Therefore, for example, silver-plated copper alloy, tin-plated copper alloy, etc. can also be used as the metal wire.

[0143] The multi-core cable has a metal shielding layer 16, which can improve the bending resistance of the multi-core cable, and can suppress signal leakage to the outside and the intrusion of radio waves from the outside. In addition, the multi-core cable has a metal shielding layer 16, which can shield heat from the outside and protect the core 13 from the influence of external heat. Moreover, the multi-core cable has a metal shielding layer 16, which can mechanically protect the core 13 even if the outer skin 15 is damaged.

[0144] [Example]

[0145] Hereinafter, specific examples will be given for description, but the present invention is not limited to these examples.

[0146] (Evaluation method)

[0147] First, a method for evaluating electric wires produced in the following experimental examples will be described.

[0148] (1) Wire diameter, outer diameter, and thickness of each layer

[0149] Regarding the wire diameter of the conductor wire and the outer diameter of each part, the lengths of two orthogonal diameters of each part to be measured in any cross section perpendicular to the longitudinal direction of the wire or multi-core cable are measured and the average value is taken.

[0150] The thickness of each layer, for example, the thickness of the outer skin 15 shown in Table 2 is set to a value obtained by subtracting the outer diameter of the crimped layer 14 from the outer diameter of the outer skin 15 and dividing the value by 2, wherein the crimped layer 14 is a layer that is in contact with the outer skin 15 and is located on the inner side of the outer skin 15. The thickness of the insulator of each electric wire is similarly set to a value obtained by subtracting the outer diameter of the conductor from the outer diameter of the insulator and dividing the value by 2, wherein the conductor is a layer that is in contact with the insulator and is located on the inner side of the insulator.

[0151] (2) Twist length

[0152] When measuring the lay length, other covering components are removed in such a way that the layer to be measured among the layers possessed by the core is exposed. Next, the lay length of each layer is measured according to JIS C 3005 (2014), and the lay length ratio of each layer is calculated. The lay length ratio of each layer possessed by the core is shown in the "lay length ratio" column of Table 1.

[0153] (3) Oil resistance

[0154] The oil resistance test was carried out according to the following procedure.

[0155] The multi-core cables prepared in each experimental example were immersed in oil for 20 hours. Then, the multi-core cables were taken out of the oil, and the insulation resistance of the insulators of all the wires included in the multi-core cables was measured according to JIS C 3005 (2014). For all the wires included in the multi-core cable, when the insulation resistance was greater than or equal to 10 MΩ / km, it was evaluated as A, and when the insulation resistance was greater than or equal to 9 MΩ / km and less than 10 MΩ / km, it was evaluated as B. For at least a portion of the wires included in the multi-core cable, when the insulation resistance was less than 9 MΩ / km, it was evaluated as C.

[0156] When the oil resistance test is evaluated as A, it can be said that the multi-core cable has the best oil resistance, and the oil resistance decreases in the order of evaluation B and C. When the oil resistance is evaluated as A or B, it can be evaluated as a multi-core cable with sufficient oil resistance. When the oil resistance is evaluated as C, it can be evaluated as a multi-core cable with insufficient oil resistance.

[0157] (4) Bending resistance

[0158] The bending resistance test was carried out according to the following procedure.

[0159] like Figure 4 As shown, the multi-core cable 40 to be evaluated is arranged in the vertical direction and clamped between two first mandrels 411 and second mandrels 412 of diameter 60 mm arranged horizontally and parallel to each other. And, the following process is repeatedly performed: after the upper end of the multi-core cable 40 is bent 90° in the horizontal direction in a manner abutting against the upper side of the first mandrel 411, the upper end of the multi-core cable 40 is bent 90° in the horizontal direction in a manner abutting against the upper side of the second mandrel 412. This repetition is performed while measuring the resistance value of the conductors of all the wires in the multi-core cable, and for any one of the wires, the number of bending times when the resistance rises to more than ten times the initial resistance value is set as an index value of the bending resistance test. Regarding the number of bending times evaluated in the above-mentioned bending resistance test, the number of bending times evaluated is from the number of times the multi-core cable 40 is bent to the number of times the resistance value is increased. Figure 4 It should be noted that during the bending resistance test, the Figure 4 The hollow arrow 42 in FIG. 4 applies a load of 5 N downward to the multi-core cable 40 .

[0160] The index value of the bending resistance test, that is, the evaluation was A when the number of bending times was equal to or greater than 50,000 times, B when the number of bending times was equal to or greater than 40,000 times and less than 50,000 times, and C when the number of bending times was less than 40,000 times.

[0161] When the evaluation of the bending resistance test is A, it can be said that the multi-core cable has the best bending resistance, and the bending resistance decreases in the order of evaluation B and C. When the evaluation of the bending resistance test is A or B, it can be evaluated as a multi-core cable with sufficient bending resistance. When the evaluation of the bending resistance test is C, it can be evaluated as a multi-core cable with insufficient bending resistance.

[0162] Hereinafter, the multi-core cable in each experimental example will be described.

[0163] Experimental Examples 1 to 5 are examples, and Experimental Examples 6, 7, and 8 are comparative examples.

[0164] (Experimental Example 1)

[0165] As shown in the multi-core cable composition column of Table 1, a multi-core cable having a cross section perpendicular to the longitudinal direction is produced. Figure 1 The multi-core cable 10 shown is a multi-core cable A having the same structure.

[0166] Table 2 shows the configuration of the multi-core cable A, and Table 3 shows the configuration of the electric wires A included in the cores of the multi-core cable A.

[0167] Table 1 shows the evaluation results.

[0168] (Experimental Example 2)

[0169] Make a cross section perpendicular to the length direction with Figure 3 The multi-core cable 30 shown is a multi-core cable B with the same structure.

[0170] The structure of the multi-core cable B is shown in Table 4, and the structure of the electric wires B included in the core of the multi-core cable B is shown in Table 5. As shown in Table 5, the electric wires B include first electric wires, second electric wires, and third electric wires having different structures, and the first electric wire is a twisted pair of two electric wires twisted together.

[0171] Table 1 shows the evaluation results.

[0172] (Experimental Example 3)

[0173] The cross section perpendicular to the longitudinal direction is produced to have the same structure as the core 13 except that the number of wires included in the core 13 is different. Figure 1 The multi-core cable 10 shown is a multi-core cable C having the same structure as that of the multi-core cable 10 .

[0174] Table 6 shows the configuration of the multi-core cable C, and Table 7 shows the configuration of the electric wires C included in the cores of the multi-core cable C.

[0175] Table 1 shows the evaluation results.

[0176] (Experimental Example 4, Experimental Example 5, Experimental Example 7, Experimental Example 8)

[0177] A multi-core cable was produced under the same conditions as those in Experimental Example 1 except that the lay ratio of each layer of the core 13 was set to the lay ratio shown in Table 1, and was evaluated.

[0178] Table 1 shows the evaluation results.

[0179] (Experimental Example 6)

[0180] A multi-core cable was produced and evaluated under the same conditions as in Experimental Example 1 except that a PP (Polypropylene) rope (rope made of polypropylene) was used as the material of the oil-absorbing filler.

[0181] The oil absorption of PP rope is less than ten times of its own weight and it is not oil-absorbent. Therefore, PP rope is not an oil-absorbent filler and can be marked as a filler only.

[0182] Table 1 shows the evaluation results.

[0183] [Table 1]

[0184]

[0185] [Table 2]

[0186]

[0187] [Table 3]

[0188]

[0189] [Table 4]

[0190]

[0191] [Table 5]

[0192]

[0193] [Table 6]

[0194]

[0195] [Table 7]

[0196]

Claims

1. A multi-core cable having: Oil-absorbing fillers; and a core configured to surround the oil-absorbing filler, the core being formed by twisting a plurality of wires, In a cross section of the core perpendicular to the longitudinal direction, the core has a plurality of layers formed by the plurality of electric wires arranged circumferentially, the innermost layer of the layers being closest to the oil-absorbing filler, The lay length of the electric wires in the innermost layer is equal to or greater than 0.45 times the lay length of the electric wires in the outermost layer of the layers and less than 0.8 times the lay length of the electric wires in the outermost layer of the layers.

2. The multi-core cable according to claim 1, wherein: The electric wire has a conductor and an insulator covering the conductor. The insulator contains a resin material having polyvinyl chloride or polyolefin as a main component.

3. The multi-core cable according to claim 1 or 2, wherein: The core has three or more layers formed of the electric wires, The lay length of the wires in the intermediate layer adjacent to the outermost layer and arranged closer to the oil-absorbing filler than the outermost layer is greater than or equal to 0.7 times the lay length of the wires in the outermost layer and less than 0.95 times the lay length of the wires in the outermost layer.

4. The multi-core cable according to claim 1 or 2, wherein: The multi-core cable also has a sheath covering the cores. The outer skin contains a resin material having polyvinyl chloride or polyolefin as a main component.

5. The multi-core cable according to claim 4, wherein: The multi-core cable has a crimping layer between the core and the sheath, The crimping layer includes an oil-absorbent tape.

6. The multi-core cable according to claim 5, wherein: The multi-core cable also has a metal shielding layer between the outer sheath and the crimping layer.

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