cable

Abstract

Provided are cables (10, 20, 30, 40, 50, 60, 70, 80) each having a plurality of covered electric wires (11) and an outer skin (13) which covers the plurality of covered electric wires (11), wherein: the outer skin (13) includes a first outer skin (131) and a second outer skin (132) in this order from the outer surface side; and the second outer skin (132) has a smaller elastic modulus than that of the first outer skin.

Description

[Technical Field]

[0001] The present disclosure relates to cables. [Background technology]

[0002] Patent Document 1 discloses a cable having a bundle of electric wires and an outer sheath that covers the bundle of electric wires, the electric wire bundle includes a first electric wire having one core, a second electric wire having one core, a twisted pair electric wire having two cores, a third electric wire having one core, and one linear inclusion formed into a linear shape by stranding a polymer; The wire bundle has, in cross section, the twisted pair electric wires are arranged on one side of a center line connecting a center of the first electric wire and a center of the second electric wire, the third electric wire and the linear inclusion are arranged on the other side of the center line. A composite cable is disclosed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2020 / 111162 Summary of the Invention

[0004] The cable of the present disclosure comprises a plurality of coated electric wires; an outer sheath covering the plurality of coated electric wires, The outer jacket includes a first outer jacket and a second outer jacket in this order from the outer surface side, The second outer cover has a lower modulus of elasticity than the first outer cover. [Brief explanation of the drawings]

[0005] [Figure 1] FIG. 1 is a cross-sectional view of a cable according to one embodiment of the present disclosure taken along a plane perpendicular to the longitudinal direction thereof. [Figure 2] FIG. 2 is a cross-sectional view of a cable according to one embodiment of the present disclosure taken along a plane perpendicular to the longitudinal direction. [Figure 3] FIG. 3 is a cross-sectional view of a cable according to one embodiment of the present disclosure taken along a plane perpendicular to the longitudinal direction. [Figure 4] FIG. 4 is a cross-sectional view of a cable according to one embodiment of the present disclosure taken along a plane perpendicular to the longitudinal direction. [Figure 5] FIG. 5 is a cross-sectional view of a cable according to one embodiment of the present disclosure taken along a plane perpendicular to the longitudinal direction. [Figure 6] FIG. 6 is a cross-sectional view of a cable according to one embodiment of the present disclosure taken along a plane perpendicular to the longitudinal direction. [Figure 7A] FIG. 7A is an explanatory diagram illustrating a state in which a cable according to one embodiment of the present disclosure is fixed by a fixture. [Figure 7B] FIG. 7B is an explanatory diagram illustrating a state in which the cable according to the embodiment of the present disclosure is fixed by a fixture. [Figure 8] FIG. 8 is an explanatory diagram of the bending resistance test. DETAILED DESCRIPTION OF THE INVENTION

[0006] [Problem to be solved by this disclosure] Cables installed in automobiles are fixed to the vehicle body at several points. Depending on the cable wiring location, the cable may be repeatedly bent at the points where it is fixed to the vehicle body. When the cable is bent, force is concentrated at the fixed points of the cable, which can cause it to break.

[0007] For this reason, there has been a demand for a cable including a plurality of covered electric wires that can be prevented from breaking even when repeatedly bent.

[0008] An object of the present disclosure is to provide a cable that can suppress breakage even when repeatedly bent.

[0009] [Effects of this disclosure] According to the present disclosure, a cable can be provided that can suppress breakage even when repeatedly bent.

[0010] The embodiments for carrying out the invention are described below.

[0011] [Description of the embodiments of the present disclosure] First, embodiments of the present disclosure will be listed and described. In the following description, the same or corresponding elements will be denoted by the same reference numerals, and the same description thereof will not be repeated.

[0012] (1) A cable according to one aspect of the present disclosure includes: a plurality of coated electric wires; an outer sheath covering the plurality of coated electric wires, The outer jacket includes a first outer jacket and a second outer jacket in this order from the outer surface side, The second outer cover has a lower modulus of elasticity than the first outer cover.

[0013] By making the elastic modulus of the second outer jacket located on the inner periphery of the outer jacket smaller than that of the first outer jacket located on the outer periphery, even when force is applied to the cable and it is repeatedly bent, the second outer jacket can deform and absorb the force, thereby reducing the force applied to the multiple insulated electric wires due to bending and preventing the insulated electric wires from breaking even when the cable is repeatedly bent.

[0014] The outer jacket functions to protect the covered wire inside the cable. As described above, the outer jacket includes at least two layers, a first outer jacket and a second outer jacket. By using the second outer jacket as a layer to absorb forces applied to the cable, it is possible to increase the elastic modulus of the first outer jacket and improve the mechanical strength of the cable. Cables installed in automobiles must be abrasion-resistant against friction with the vehicle body, scratch-resistant to scratches caused by flying stones, and flexible enough to withstand repeated bending with minimal deterioration. These requirements can be met by increasing the mechanical strength of the outer jacket.

[0015] (2) The modulus of elasticity of the second outer cover may be 40% or more and 80% or less of the modulus of elasticity of the first outer cover.

[0016] By setting the elastic modulus of the second outer sheath to 80% or less of the elastic modulus of the first outer sheath, the flexibility of the cable can be increased, and when force is applied to the cable and it is repeatedly bent, the force applied to the cable can be absorbed and the insulated wire can be prevented from breaking.

[0017] By setting the elastic modulus of the second outer jacket to at least 40% of the elastic modulus of the first outer jacket, the second outer jacket can be manufactured by extrusion molding, which increases the productivity of the cable and reduces costs.

[0018] (3) The first outer cover may have an elastic modulus of 33 MPa or more and 55 MPa or less.

[0019] By setting the modulus of elasticity of the first jacket to 55 MPa or less, the cable can have flexibility suitable for wiring in an automobile.

[0020] By setting the modulus of elasticity of the first outer sheath to 33 MPa or more, the mechanical strength of the first outer sheath can be made high enough for use in automotive wiring.

[0021] (4) The second outer cover may be a foam.

[0022] By making the second outer sheath a foam, the second outer sheath can be easily deformed, and when external pressure is applied to a part of the cable, the second outer sheath collapses under the pressure and can absorb the pressure.

[0023] (5) The plurality of insulated electric wires may include insulated electric wires having different conductor cross-sectional areas.

[0024] By making the cable include coated wires with different conductor cross-sectional areas, the cable can be used for a variety of purposes.

[0025] (6) The plurality of insulated electric wires may include two insulated electric wires having the same conductor cross-sectional area, and the two insulated electric wires may be twisted together.

[0026] Twisted pair wires, which are made by twisting together two covered wires with the same conductor cross-sectional area, can be used as signal transmission wires (signal wires) for sensors and other applications. Twisted pair wires have the advantage of being able to suppress the deterioration and attenuation of the transmitted signal. Another advantage of twisted pair wires is that they can be handled together when wiring in the same location, making wiring easier.

[0027] (7) In a cross section perpendicular to the longitudinal direction, the outer periphery of the second outer cover may have a circularity of 97% or more.

[0028] By making the outer periphery of the second jacket 97% or more round, the outer shape of the cable can be made round. When the cable is introduced into another member such as a box, the round outer shape of the cable, i.e., close to a perfect circle, prevents gaps from forming between the cable and the inlet of the other member, allowing the cable to be firmly fixed. Furthermore, because the outer shape of the cable is round, when the cable is introduced into the housing of a device, the gap between the cable and the housing can be easily sealed at the introduction portion, preventing gaps from forming between the cable and the housing.

[0029] [Details of the embodiments of the present disclosure] Specific examples of cables according to an embodiment of the present disclosure (hereinafter referred to as "the present embodiment") will be described below with reference to the drawings. Note that the present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims. (1) Cable components First, the cable of this embodiment will be described with reference to FIGS. 1 to 7B.

[0030] FIG. 1 shows a cross-sectional view of cable 10 of this embodiment taken along a plane perpendicular to the longitudinal direction. Also, FIGS. 2 to 6 show cross-sectional views of cables 20 to 60 of this embodiment taken along a plane perpendicular to the longitudinal direction. Since FIGS. 2 to 6 show modified examples of the coated wires and jacket configurations of the cables of this embodiment, the cable of this embodiment will be described mainly using FIG. 1, and will also be described using FIGS. 2 to 6 as necessary. FIGS. 7A and 7B are explanatory diagrams of a state in which cable 70 of this embodiment is fixed by a fixture 71. FIG. 7A corresponds to a cross-sectional view taken along line AA in FIG. 7B. In FIGS. 1 to 7B, the Z-axis direction is the longitudinal direction of the cable or coated wire, and the XY plane is a cross section perpendicular to the longitudinal direction of the cable, etc.

[0031] As shown in FIG. 1, a cable 10 of this embodiment includes a plurality of coated electric wires 11 and an outer sheath 13 that covers the coated electric wires 11.

[0032] 1 shows an example in which the cable 10 has two first covered electric wires 111 and two second covered electric wires 112 as the covered electric wires 11, but the configuration of the multiple covered electric wires in the cable of this embodiment is not limited to this form. The cable of this embodiment can include any number of covered electric wires, and the combination of types of covered electric wires contained in the cable can also be selected freely.

[0033] The components of the cable 10 of this embodiment will be described below. (1-1) Insulated wire The coated electric wire 11 is an electric wire that performs functions required in devices, such as power supply, voltage application, and communication, and is an electric wire that is a target for preventing breakage. As described above, the number and configuration of the coated electric wire 11 are not particularly limited.

[0034] The coated electric wire 11 may have a conductor and an insulator covering the outer periphery of the conductor. The conductor may be a stranded wire in which a plurality of conductor wires are twisted together.

[0035] The first coated electric wire 111 has a conductor 1111 which is a twisted wire of conductor wires 1111A, and an insulator 1112 which coats the outer periphery of the conductor 1111. The first coated electric wire 111 can be, for example, a power line intended to supply electric current.

[0036] The second coated electric wire 112 has a conductor 1121 which is a twisted wire of conductor wires 1121A, and an insulator 1122 which coats the outer periphery of the conductor 1121. The second coated electric wire 112 can be, for example, a signal wire intended for transmitting signals.

[0037] 1 , the cable of this embodiment can include multiple covered electric wires 11 having different conductor cross-sectional areas, such as the first covered electric wire 111 and the second covered electric wire 112. By including covered electric wires 11 having different conductor cross-sectional areas in this way, the cable can be made applicable to a variety of uses. In the cable 10 of this embodiment, the conductor cross-sectional area of ​​the first covered electric wire 111 can be made larger than the conductor cross-sectional area of ​​the second covered electric wire 112.

[0038] In the case of the first coated electric wire 111, the conductor cross-sectional area of ​​the coated electric wire 11 is a value including the cross-sectional area of ​​the conductor element wires 1111A that make up the conductor 1111.

[0039] In the case of the second coated electric wire 112, the cross-sectional area of ​​the conductor 1121 is the combined value of the cross-sectional areas of the conductor wires 1121A that make up the conductor 1121.

[0040] In the cable 10 shown in Fig. 1, the insulated electric wires 11 include two first insulated electric wires 111 and two second insulated electric wires 112 as described above, but the present invention is not limited to this. Below, configuration examples of the insulated electric wires in other cables shown in Figs. 2 to 5 will be described. Note that the configuration examples of the insulated electric wires in the cables shown in Figs. 2 to 5 are also merely illustrative, and the present invention is not limited to these examples. (For cable 20) The cable 20 shown in FIG. 2 has, as the coated electric wires 11, two first coated electric wires 111, two second coated electric wires 112, and two third coated electric wires 113.

[0041] The third coated wire 113 has a conductor 1131 and an insulator 1132 that coats the conductor 1131 .

[0042] In FIG. 2, the third coated electric wire 113 shows an example in which a solid wire is used as the conductor 1131 instead of a twisted wire, but this is not limited to this form, and a twisted wire in which multiple conductor wires are twisted together can also be used as the conductor 1131.

[0043] 2, the multiple covered electric wires 11 include a second covered electric wire 112, which is two covered electric wires 11 having the same conductor cross-sectional area. The second covered electric wire 112, which is the two covered electric wires 11, may be twisted together. That is, the second covered electric wire 112 may be a twisted pair electric wire 21.

[0044] A twisted pair electric wire (twisted pair wire) made by twisting together two covered electric wires 11 with the same conductor cross-sectional area can be used as an electric wire (signal wire) for signal transmission, such as an electric wire for a sensor. Twisted pair electric wires have the advantage of being able to suppress deterioration and attenuation of the transmitted signal. Another advantage of twisted pair electric wires is that they can be handled together when wiring in the same location, making wiring easier. (For cable 30) The cable 30 shown in FIG. 3 has, as the coated electric wires 11, two first coated electric wires 111, two second coated electric wires 112, and one third coated electric wire 113.

[0045] The cable 30 can have the same configuration as the cable 20 shown in FIG. 2 except that the number of third coated electric wires 113 is different. (For cable 40) The cable 40 shown in FIG. 4 has two first covered electric wires 111 and four second covered electric wires 112 as the covered electric wires 11.

[0046] In the cable 40 shown in Fig. 4, four second covered electric wires 112 can be twisted two by two to form a twisted pair electric wire 21. As shown in the cable 40 as an example, the cable of this embodiment can also include multiple pairs of twisted covered electric wires. In Fig. 4, the two twisted pair electric wires 21 are arranged symmetrically with respect to an imaginary line L40 connecting the centers of the two first covered electric wires 111 as an axis of symmetry. This arrangement makes it possible to make the collective diameter of the covered electric wires 11 included in the cable 40 as small as possible and to make the outer shape of the twisted covered electric wires 11 as round as possible. (For cable 50) The cable 50 shown in FIG. 5 has two first covered electric wires 111, two third covered electric wires 113, and two fourth covered electric wires 114 as the covered electric wires 11.

[0047] The fourth covered electric wire 114 has a conductor 1141 which is a strand of conductor wires, and an insulator 1142 which covers the outer periphery of the conductor 1141 .

[0048] Two third covered electric wires 113 having the same conductor cross-sectional area are twisted together to form a twisted pair electric wire 51. A covering 52 may be provided to cover the twisted pair electric wire 51. Fig. 5 shows an example in which a first covering 521 and a second covering 522 are arranged from the twisted pair electric wire 51 side as the covering 52. The covering 52 may be made up of one layer, or may be made up of three or more layers.

[0049] As the material of the first coating 521, for example, one or more types selected from thermoplastic polyurethane elastomer, ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer (EEA), and the like can be suitably used.

[0050] As the material of the second coating 522, for example, a thermoplastic polyurethane elastomer or the like can be suitably used.

[0051] The covering 52 may be formed by covering the twisted pair wire 51 with insulating resin by solid extrusion molding as shown in FIG. 5, or may be a resin tube (not shown).

[0052] (Examples of insulated wire configurations) The diameter and number of conductor wires constituting the conductor of the insulated electric wire can be selected depending on the electrical properties required for each insulated electric wire.

[0053] For example, the diameter of the conductor wires of the coated electric wire 11 is preferably 0.05 mm or more and 0.16 mm or less, and more preferably 0.05 mm or more and 0.10 mm or less. The power line can also be made by twisting conductor wires together in multiple stages. For example, the conductor of the power line can have a first twisted wire (child twisted wire) made by twisting conductor wires together, and a second twisted wire (parent twisted wire) made by twisting multiple first twisted wires together. The conductor can also be a third twisted wire made by further twisting multiple second twisted wires together. In this case, the first twisted wire is sometimes called a grandchild twisted wire, the second twisted wire is sometimes called a child twisted wire, and the third twisted wire is sometimes called a parent twisted wire.

[0054] The signal conductor can also be formed by twisting conductor wires together in multiple stages. That is, the conductor of the signal conductor can have a first twisted wire (child twisted wire) made by twisting conductor wires together, and a second twisted wire (parent twisted wire) made by twisting multiple first twisted wires together. The second twisted wire can be the conductor, or a third twisted wire, for example, made by further twisting multiple second twisted wires, can also be the conductor. The conductor wire of the signal conductor can be single twisted, or the first twisted wire can be the conductor.

[0055] The wire diameter of a wire such as a conductor wire can be measured and calculated, for example, by the following procedure.

[0056] First, in an arbitrary cross section perpendicular to the longitudinal direction of the wire, the wire diameter is measured using a micrometer along two orthogonal diameters of the wire. The average value of these measurements can be used as the wire diameter of the wire. In this specification, the wire diameter of a wire can be measured and calculated in the same manner.

[0057] When the cable has a power line and a signal line as the coated electric wire 11, the conductor cross-sectional area of ​​the conductor of the power line is set to 1.5 mm 2 More than 3.5mm 2In this case, the cross-sectional area of ​​the conductor of the signal line is set to 0.1 mm 2 More than 0.5mm 2 The following forms can be exemplified.

[0058] The cross-sectional area of ​​the conductor of the power line is preferably larger than that of the conductor of the signal line, and more preferably is 3 to 15 times the cross-sectional area of ​​the conductor of the signal line.

[0059] The material of the conductor wires of the coated electric wire 11 is not particularly limited, but examples thereof include copper, aluminum, copper alloys, and aluminum alloys. The surfaces of the conductor wires may be plated with silver or tin. Therefore, the conductor wires may be made of, for example, a silver-plated copper alloy or a tin-plated copper alloy.

[0060] The material of the insulator is not particularly limited, and may be one or more resins selected from fluororesins such as polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), ethylene-tetrafluoroethylene copolymer (ETFE), polyester resins such as polyethylene terephthalate (PET), polyolefin resins such as polyethylene and polypropylene, etc. The resin of the insulator may or may not be crosslinked.

[0061] In addition to the above resins, the insulator may also contain additives such as flame retardants, flame retardant assistants, antioxidants, lubricants, colorants, reflectivity imparting agents, opacifying agents, processing stabilizers, and plasticizers. (core) The cable 10 can include a core 10A including a plurality of covered electric wires 11. The core 10A can be formed by twisting together the above-mentioned plurality of covered electric wires 11, specifically, two first covered electric wires 111 and two second covered electric wires 112, along the longitudinal direction.

[0062] The cables 20 to 50 may also contain cores.

[0063] The cable 20 has a core 20A in which two first covered electric wires 111, two second covered electric wires 112, and two third covered electric wires 113 are twisted together in the longitudinal direction. The two second covered electric wires 112 are twisted together in advance as described above.

[0064] The cable 30 has a core 30A in which two first covered electric wires 111, two second covered electric wires 112, and one third covered electric wire 113 are twisted together in the longitudinal direction. The two second covered electric wires 112 are twisted together in advance as described above.

[0065] The cable 40 has a core 40A in which two first covered electric wires 111 and four second covered electric wires 112 are twisted together in the longitudinal direction. As described above, the second covered electric wires 112 are twisted together in pairs in advance.

[0066] The cable 50 has a core 50A in which two first covered electric wires 111, two third covered electric wires 113, and two fourth covered electric wires 114 are twisted together in the longitudinal direction. The two third covered electric wires 113 are twisted together in advance as described above.

[0067] The arrangement of the multiple insulated electric wires 11 that make up the core is not particularly limited, and the arrangement of each insulated electric wire can be selected, for example, so that the circumscribed circle of the multiple insulated electric wires 11 approaches a perfect circle in a cross section perpendicular to the longitudinal direction of the cable.

[0068] The twisting direction and twisting pitch of the core are not particularly limited and can be selected arbitrarily.

[0069] (1-2) Outer covering The cable 10 may have an outer jacket 13 that covers a plurality of coated wires.

[0070] When a cable is laid, the cable 70 may be fixed to the body of an automobile using a fixture 71 as shown in FIGS. 7A and 7B . At this time, as shown in FIGS. 7A and 7B , the cable 70 is fastened at the portion of the fixture 71 where the cable 70 is fastened so that the minor diameter D71 of the fixture 71 is shorter than the outer diameter of the cable 70 before fastening. Specifically, for example, the fixture 71 is fastened so that the minor diameter D71 is shorter than the outer diameter of the cable 70 before fastening by approximately 10% to 20%. Therefore, the cable 70 may be pressed by the fixture 71 and fastened in a deformed state. Note that FIG. 7A shows a cross section perpendicular to the longitudinal direction of the cable 70, and FIG. 7B shows a perspective view of the cable 70. The sheathed wires and other components of the cable 70 are not shown in FIG. 7A . Furthermore, the length L71 (see FIG. 7B) of fixture 71 in the longitudinal direction of cable 70 is usually selected to be, for example, between one and three times the outer diameter of cable 70.

[0071] As described above, force may be applied to cable 70 while it is fixed by fixture 71, causing cable 70 to bend repeatedly. However, according to studies by the inventors of the present invention, bending force tends to concentrate on the portion of cable 70 that is fixed by fixture 71. Therefore, breakage is likely to occur at the portion that is fixed by fixture 71.

[0072] Therefore, the inventors of the present invention conducted further research and found that by making the outer sheath 13 have at least a two-layer structure and providing a layer that is easily deformed, the external force applied when bending can be absorbed, the force applied to the multiple coated electric wires 11 can be reduced, and breakage can be reduced, thereby completing the present invention. (Outer shell structure) The sheath 13 of the cable 10 of this embodiment includes a first sheath 131 and a second sheath 132 in this order from the outer surface 13A side.

[0073] The first outer sheath 131 is a layer including the outer surface 13A of the sheath 13, and is the layer disposed on the outermost side. The second outer sheath 132 is a layer disposed closer to the core 10A than the first outer sheath 131. The sheath 13 is not limited to having only two layers, the first outer sheath 131 and the second outer sheath 132, but may be configured with three or more layers. The sheath 13 may also have a third outer sheath 133 (see cable 60 in FIG. 6) or the like, located closer to the core 10A than the second outer sheath 132, for example.

[0074] The second outer cover 132 of the outer cover 13 has a smaller elastic modulus than the first outer cover 131.

[0075] In this way, by making the modulus of elasticity of the second outer sheath 132 located on the inner periphery of the outer sheath 13 smaller than that of the first outer sheath 131 located on the outer periphery, even when force is applied to the cable 10 and it is repeatedly bent, the second outer sheath 132 can deform and absorb the force. This reduces the force applied to the multiple insulated electric wires 11 due to bending, and prevents the insulated electric wires 11 from breaking even when the cable 10 is repeatedly bent.

[0076] The outer sheath 13 functions to protect the coated wires 11 inside the cable 10. As described above, the outer sheath 13 includes at least two layers, the first outer sheath 131 and the second outer sheath 132. By having the second outer sheath 132 function as a layer for absorbing forces applied to the cable, it is possible to increase the elastic modulus of the first outer sheath 131 and thereby enhance the mechanical strength of the cable 10. Cables installed in automobiles are required to be abrasion-resistant against friction with the vehicle body, scratch-resistant to scratches caused by flying stones, and flexible to withstand repeated bending with minimal deterioration. These requirements can be met by increasing the mechanical strength of the outer sheath 13.

[0077] In this specification, the term "elastic modulus" refers to the tensile modulus measured at 23°C.

[0078] Each layer of the jacket 13 will be described below.

[0079] (first outer covering) The elastic modulus of first outer cover 131 is not particularly limited as long as it is greater than the elastic modulus of second outer cover 132, but it is preferable that the elastic modulus of first outer cover 131 be 33 MPa or more and 55 MPa or less.

[0080] By setting the elastic modulus of first jacket 131 to 55 MPa or less, cable 10 can have flexibility suitable for wiring in an automobile.

[0081] By setting the modulus of elasticity of first outer sheath 131 to 33 MPa or more, the mechanical strength of first outer sheath 131 can be made high enough for use in wiring for automobiles.

[0082] The material of the first outer cover 131 is not particularly limited, but the first outer cover 131 may include, for example, a thermoplastic polyurethane elastomer. The resin of the first outer cover 131 may be crosslinked or may not be crosslinked.

[0083] In addition to the above resins, the first outer cover 131 may contain additives such as flame retardants, flame retardant assistants, antioxidants, lubricants, colorants, reflectivity imparting agents, opacifying agents, processing stabilizers, and plasticizers. (Second outer covering) The modulus of elasticity of the second outer cover 132 can be set to be smaller than the modulus of elasticity of the first outer cover 131 as described above.

[0084] The elastic modulus of the second outer cover 132 is preferably, for example, 40% to 80% of the elastic modulus of the first outer cover 131. An elastic modulus within this range can be achieved by using a material with an elastic modulus within this range or by adjusting the foaming degree of the second outer cover.

[0085] By setting the modulus of elasticity of the second outer sheath 132 to 80% or less of the modulus of elasticity of the first outer sheath 131, the flexibility of the cable 10 can be increased, and when force is applied to the cable 10 and it is repeatedly bent, the force applied to the cable 10 can be absorbed, and the insulated electric wire 11 can be prevented from breaking.

[0086] By setting the modulus of elasticity of second outer sheath 132 to be 40% or more of the modulus of elasticity of first outer sheath 131, second outer sheath 132 can be manufactured by extrusion molding, which increases the productivity of cable 10 and reduces costs.

[0087] The material of the second outer cover 132 is not particularly limited, but the second outer cover 132 may include, for example, a thermoplastic polyurethane elastomer or a foamed thermoplastic polyurethane elastomer. The resin of the second outer cover 132 may or may not be crosslinked.

[0088] In addition to the above resins, the second outer cover 132 may also contain additives such as flame retardants, flame retardant assistants, antioxidants, lubricants, colorants, reflectivity imparting agents, opacifying agents, processing stabilizers, and plasticizers.

[0089] The second skin 132 may also be foam.

[0090] By making the second outer sheath 132 from a foam, the second outer sheath 132 can be easily deformed, and when external pressure is applied to a part of the cable 10, the second outer sheath 132 collapses under the pressure and can absorb the pressure.

[0091] The roundness of outer periphery 132A of second jacket 132 in a cross section perpendicular to the longitudinal direction of cable 10 is not particularly limited, but is preferably 97% or more.

[0092] By making the circularity of the outer periphery 132A of the second outer jacket 132 97% or more, the outer shape of the cable 10 can be made round, for example, nearly perfect circular. When the cable 10 is introduced into another member such as a box, the round, i.e., nearly perfect circular, outer shape of the cable 10 can prevent a gap from being formed between the cable 10 and the intake port of the other member, thereby firmly fixing the cable 10. Furthermore, because the outer shape of the cable 10 is round, when the cable 10 is introduced into the housing of a device, the gap between the cable 10 and the housing can be easily sealed at the introduction portion, preventing a gap from being formed between the cable 10 and the housing.

[0093] There is no particular limitation on the method for setting the circularity of the outer periphery 132A of the second outer sheath 132 within the above range, but examples include a method of providing a third outer sheath 133 as described below, and a method of making the second outer sheath 132 sufficiently thick and adjusting the circularity of the second outer sheath 132.

[0094] The circularity is determined by taking the ratio of the diameters in two orthogonal axial directions in any cross section perpendicular to the longitudinal direction of the cable. The circularity of outer periphery 132A of second jacket 132 is preferably measured and calculated in multiple cross sections perpendicular to the longitudinal direction of the cable, and the average value of the circularities calculated in the multiple cross sections is used.

[0095] For example, in the cross section of cable 10 shown in FIG. 1, the outer diameter of second outer sheath 132 is measured along the X-axis and the Y-axis, and the roundness of outer periphery 132A of second outer sheath 132 in that cross section is calculated as the ratio of the outer diameter along the X-axis to the outer diameter along the Y-axis. Similarly, the roundness of outer periphery 132A of second outer sheath 132 in multiple other cross sections can be calculated, and the average of the roundnesses in the multiple measured cross sections can be used as the roundness of outer periphery 132A of second outer sheath 132 of the cable. When measuring the roundness in multiple cross sections as described above, it is preferable that the directions of the X-axis and Y-axis are constant. That is, it is preferable that the X, Y, and Z axes are fixed over the entire length of cable 10 to be measured, and evaluation is performed according to the above procedure.

[0096] The distance between the multiple cross sections to be evaluated is preferably constant. The number of cross sections to be evaluated is not particularly limited, and is preferably, for example, three or more.

[0097] The circularity is more preferably, for example, 97% or more and 103% or less. (Third outer covering) As described above, the outer sheath 13 can include not only two layers, the first outer sheath 131 and the second outer sheath 132, but also three or more layers. For example, the outer sheath 13 can have a third outer sheath 133. When the outer sheath 13 has the third outer sheath 133, the third outer sheath 133 can be arranged closer to the core 10A than the second outer sheath 132, as shown in FIG. 6, for example. Note that the cable 60 shown in FIG. 6 has the same structure as the cable 10 shown in FIG. 1 except that the outer sheath 13 has the third outer sheath 133, and therefore a description of the other points will be omitted.

[0098] By providing the third outer sheath 133 to the outer sheath 13, the roundness of the cable can be improved.

[0099] The material of the third outer cover 133 is not particularly limited, but may include one or more resins selected from thermoplastic polyurethane elastomer (TPU) and polyolefin resins such as ethylene-vinyl acetate copolymer resin (EVA) and ethylene-ethyl acrylate copolymer resin (EEA). The resin of the third outer cover 133 may be crosslinked or may not be crosslinked.

[0100] In addition to the above resins, the third outer cover 133 may contain additives such as flame retardants, flame retardant assistants, antioxidants, lubricants, colorants, reflectivity imparting agents, opacifying agents, processing stabilizers, and plasticizers.

[0101] (1-3) Pressing winding The cable 10 of this embodiment may also have a pressure winding 12 that covers the outer periphery of the core 10A. A suitable example of the pressure winding 12 is a tape made of an insulating material such as paper, nonwoven fabric, or polyester resin that is spirally wound around the outer periphery of the core 10A along the longitudinal direction of the core 10A.

[0102] By placing the pressure winding 12 on the outer periphery of the core 10A, direct contact between the core 10A and the outer sheath 13 can be prevented, so that the outer sheath 13 can be easily peeled off from the core 10A when removing the coated electric wire 11 at the longitudinal end of the cable 10.

[0103] As described above, when a tape body is wound around the outer periphery of the core 10A to form the pressure winding 12, the winding direction of the pressure winding 12 can be selected arbitrarily, and for example, it may be the same as or different from the twisting direction of the core 10A described above. In particular, it is preferable that the twisting direction of the core 10A and the winding direction of the pressure winding 12 are the same direction.

[0104] Furthermore, it is preferable that the winding pitch of the pressure winding 12 is shorter than the twist pitch of the core 10A. This is because, by making the winding pitch of the pressure winding 12 shorter than the twist pitch of the core 10A, it is possible to prevent the tape forming the pressure winding 12 from dropping into recesses formed between the multiple coated electric wires 11 that make up the core 10A, and to make the surface of the pressure winding 12 smooth. (1-4) Intervention The cable 10 of this embodiment may also have a filler disposed within the area surrounded by the jacket 13, for example, within the core 10A. The filler may be made of fibers such as staple fiber or nylon thread. The filler may also be made of tensile strength fiber.

[0105] By placing an interposer within core 10A, for example, between coated wires 11, the arrangement of coated wires 11 can be adjusted, and in a cross section perpendicular to the longitudinal direction of cable 10, the circumscribing circle of core 10A and the shape of the outer surface of each layer constituting outer sheath 13 can be easily adjusted to approximate a perfect circle.

[0106] The cable of this embodiment can be used in various applications where force is applied to the cable and the cable is repeatedly bent. The cable of this embodiment can be used in devices such as automobiles where the cable is frequently bent or vibrated due to movement, for example, parking BThe wire is suitable for use in electric parking brakes that electrify a rake. In particular, it is suitable for use in applications where the impact of a break in the insulated wire is significant, such as an electric brake system that electrifies an automobile's foot brake, and where it is particularly important to prevent breakage of the insulated wire. In an electric brake system, the power line is configured to supply power for driving the motor, and the signal line is configured to transmit electrical signals related to motor control and wheel rotation speed.

[0107] (2) Evaluation method The method for evaluating the cable of this embodiment will be described below. (2-1) Elastic modulus The method for evaluating the elastic modulus of the cable jacket will be explained.

[0108] First, cut out the first and second outer jackets from the cable to be evaluated. If the outer jacket 13 includes a third outer jacket, the third outer jacket can be cut out in the same way. At this time, carefully cut out each layer so that the maximum thickness of each layer remains.

[0109] Next, each cut-out outer jacket is used to prepare a test specimen for measuring the tensile modulus in accordance with ISO 527. The thickness of the test specimen for measuring the tensile modulus should be as thick as possible from the cable. The width and length of the test specimen should be maintained at 50 mm between the gauge lines and 10 mm in width, with other dimensions being as specified or as close to the specified values ​​as possible.

[0110] The 0.25% secant modulus of elasticity at 23°C is measured for the prepared test piece, and the tensile modulus of elasticity for the test piece is determined.

[0111] (2-2) Flexibility The bending resistance of a cable, that is, the degree to which breakage of the coated wires of the cable can be suppressed when the cable is repeatedly bent, can be evaluated by the following procedure.

[0112] 8, a first end 80A side of the cable 80 to be evaluated is gripped and fixed by a first blanket 811. The first blanket 811 is fixed so as not to move during the bending resistance test.

[0113] Additionally, the second end 80B side of the cable 80 is held by the second blanket 812. When the blankets are installed, the length of the cable 80 between the first blanket 811 and the second blanket 812 is set to 200 mm. The second end 80B side of the cable 80 held by the second blanket 812 is configured to be movable in the vertical direction.

[0114] 8, the second blanket 812 is moved up and down in the vertical direction from the reference position 83A, along arrows B and C, to repeatedly bend the cable 80. The reference position 83A is located at the same height as the first blanket 811. When the first blanket 811 and the second blanket 812 are at the reference position, the distance between them is 100 mm.

[0115] The above bending can be performed repeatedly, with the second blanket 812 moving from the reference position 83A to the upper end 83B, the reference position 83A, the lower end 83C, and back to the reference position 83A in that order. The order of the upper end 83B and the lower end 83C in the above operation can also be reversed.

[0116] The distance between reference position 83A and upper end 83B and the distance between reference position 83A and lower end 83C are set equal and constant even when repeatedly bent. If the length of cable 80 between first blanket 811 and second blanket 812 is 200 mm, the distance from the reference position to the upper end or lower end should be 80 mm.

[0117] The above operation of repeatedly bending the cable 80 is performed while measuring the resistance values ​​of the conductors of all the covered electric wires 11 in the cable 80. Then, for the conductor of any of the covered electric wires 11, the number of times of bending until the resistance increases to 10 times or more the initial resistance value is recorded and used as an index value for the bending resistance test.

[0118] The index value of the bending resistance test, that is, the greater the number of bending times, the more excellent the bending resistance. (3) Cable manufacturing example An example of cable fabrication will be described below, but the present invention is not limited to the example shown below.

[0119] The fabricated cable has the same configuration as the cable 60 shown in FIG. 6 except that two second coated electric wires 112 are twisted together, and therefore will be described with reference to FIG.

[0120] The core 10A includes two first coated electric wires 111 and two second coated electric wires 112.

[0121] The first coated electric wire 111 has a conductor 1111 which is a twisted wire of conductor wires 1111A, and an insulator 1112 which coats the outer periphery of the conductor 1111. The conductor wire 1111A has a wire diameter of 0.08 mm, and the conductor cross-sectional area of ​​the conductor 1111 is 1.7 mm. 2 The insulator 1112 is made of polyethylene and has an outer diameter of 2.7 mm.

[0122] The second coated electric wire 112 has a conductor 1121 which is a twisted wire of conductor wires 1121A, and an insulator 1122 which coats the outer periphery of the conductor 1121. The conductor wire 1121A has a wire diameter of 0.08 mm, and the conductor cross-sectional area of ​​the conductor 1121 is 0.24 mm. 2 The insulator 1122 is made of polyethylene and has an outer diameter of 1.5 mm.

[0123] The two first covered electric wires 111 and the two second covered electric wires 112 are twisted together to form the core 10A. As described above, the two second covered electric wires 112 are twisted together in advance, unlike the case shown in FIG.

[0124] A tape body is wound around the outer periphery of the core 10A to form a pressure winding 12, and an outer jacket 13 is arranged to cover the outer periphery of the pressure winding 12.

[0125] The outer jacket 13 includes a first outer jacket 131, a second outer jacket 132, and a third outer jacket 133 in this order from the outer surface 13A side.

[0126] The first outer cover 131 is made of a thermoplastic polyurethane elastomer. The thickness of the first outer cover 131 is 0.2 mm. The tensile modulus of elasticity of the thermoplastic polyurethane elastomer of the first outer cover 131 at 23°C is 50 MPa.

[0127] The second outer jacket 132 is made of a foamed thermoplastic polyurethane elastomer and is 0.5 mm thick. The second outer jacket is made of the same resin as the first outer jacket, but is foamed. The elastic modulus of the second outer jacket is 50% of that of the first outer jacket.

[0128] The third outer cover 133 was made of the same thermoplastic polyurethane elastomer as the first outer cover 131. The thickness of the third outer cover 133 was 0.3 mm.

[0129] When the above-mentioned cable was subjected to the bending resistance test, it was found to be able to be bent more than 300,000 times, demonstrating excellent bending resistance, i.e., the cable is able to prevent breakage even when bent repeatedly. [Explanation of symbols]

[0130] 10, 20, 30, 40, 50, 60, 70, 80 cables 10A, 20A, 30A, 40A, 50A core 11. Insulated wire 111 First coated wire 112 Second coated wire 113 Third coated wire 114 Fourth coated wire 1111A, 1121A Conductor strands 1111, 1121, 1131, 1141 Conductors 1112, 1122, 1132, 1142 Insulators 12 Retaining coil 13 Outer sheath 131 First outer sheath 132 Second outer sheath 132A Outer periphery 133 Third outer sheath 13A Outer surface 21, 51 Twisted pair wires L40 Virtual line 52 Coating 521 First coating 522 Second coating 71 Fixture D71 Minor diameter L71 Length 80A First end 80B Second end 811 First blanket 812 Second blanket 83A Reference position 83B Upper end 83C Lower end B, C Arrows

Claims

1. A plurality of coated electric wires; an outer sheath covering the plurality of coated electric wires, The outer jacket includes a first outer jacket and a second outer jacket in this order from the outer surface side, the second outer cover has a modulus of elasticity that is smaller than the modulus of elasticity of the first outer cover; A cable in which the modulus of elasticity of the first outer sheath and the modulus of elasticity of the second outer sheath are 0.25% secant modulus of elasticity measured at 23°C.

2. The cable according to claim 1, wherein the modulus of elasticity of the second outer covering is 40% or more and 80% or less of the modulus of elasticity of the first outer covering.

3. 3. The cable according to claim 1, wherein the first outer covering has an elastic modulus of 33 MPa or more and 55 MPa or less.

4. The cable according to any one of claims 1 to 3, wherein the second jacket is a foam.

5. The cable according to claim 1 , wherein the plurality of insulated electric wires include insulated electric wires having different conductor cross-sectional areas.

6. The cable according to claim 1 , wherein the plurality of insulated electric wires include two insulated electric wires having the same conductor cross-sectional area, and the two insulated electric wires are twisted together.

7. 7. The cable according to claim 1, wherein the second outer jacket has an outer circumferential circularity of 97% or more in a cross section perpendicular to the longitudinal direction.

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