In-vehicle cable

Abstract

To provide an on-vehicle cable capable of transmitting high frequency band signals.SOLUTION: An on-vehicle cable for transmitting signals of 4GHz or higher includes: a 2-core cable; an integrated shield layer with a braided structure arranged on an outer periphery of the 2-core cable; and a jacket arranged on an outer periphery of the integrated shield layer. The 2-core cable includes: conductors which are two strands arranged in parallel; an insulator layer coating the two conductors together; and a first shield layer containing a first metal foil arranged on an outer periphery of the insulator layer.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to in-vehicle cables.

Background Art

[0002] Patent Document 1 discloses a pair of conductors arranged in parallel; a pair of coating layer bodies each provided on the outer peripheral surface of the pair of conductors by extrusion molding, each constituted by an insulating resin, and covering the periphery of the conductor, and a pair of coating layers each provided with a spiral fold integrally formed on the outer peripheral surface of the coating layer body; a pair of round pipe-shaped core outer layers each provided so as to cover the pair of coating layers, each constituted by an insulating material; a drain wire provided between the pair of core outer layers; a shield member for shielding the pair of core outer layers and the drain wire; and a twinax cable characterized by comprising the above.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A two-core cable, also called a twinax cable, has been conventionally used for signal transmission and the like, and various studies have been made for performance improvement, as disclosed in Patent Document 1, for example.

[0005] By the way, in recent years, in automobiles, autonomous driving and the application of safety equipment have been studied and put into practical use, and there has been a demand for in-vehicle cables capable of transmitting signals in a high-frequency band inside automobiles.

[0006] Therefore, an object of the present disclosure is to provide an in-vehicle cable capable of transmitting signals in a high-frequency band.

Means for Solving the Problems

[0007] The in-vehicle cable of the present disclosure is an in-vehicle cable capable of transmitting signals of 4 GHz or higher, a two-core cable, a comprehensive shield layer having a braided structure disposed on the outer periphery of the two-core cable, and an outer jacket disposed on the outer periphery of the comprehensive shield layer. The two-core cable includes conductors that are two twisted wires arranged in parallel, an insulating layer that collectively coats the two conductors, and a first shield layer including a first metal foil disposed on the outer periphery of the insulating layer.

Effects of the Invention

[0008] According to the present disclosure, an in-vehicle cable capable of transmitting signals in a high-frequency band can be provided.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4A

Figure 4B

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Mode for Carrying Out the Invention

[0010] The mode for carrying out the invention will be described below.

[0011] [Description of 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 are denoted by the same reference numerals, and the same description thereof will not be repeated.

[0012] (1) The in-vehicle cable according to one aspect of the present disclosure is an in-vehicle cable capable of transmitting signals of 4 GHz or higher, and a two-core cable, a comprehensive shield layer having a braided structure disposed on the outer periphery of the two-core cable, and an outer jacket disposed on the outer periphery of the comprehensive shield layer. The two-core cable includes conductors that are two twisted wires arranged in parallel, an insulating layer that collectively coats the two conductors, and a first shield layer including a first metal foil disposed on the outer periphery of the insulating layer.

[0013] By using twisted wires as conductors, the flexibility of the in-vehicle cable to be easily bent and the bendability that is less likely to break when repeatedly bent can be enhanced as compared with the case of single wires where the conductors are not twisted wires.

[0014] In addition, in the in-vehicle cable according to one aspect of the present disclosure, since two conductors are collectively covered, the environment of the material between the two conductors can be easily made constant. Therefore, it is possible to sufficiently suppress the insertion loss of signals in the high-frequency region of 4 GHz or higher, and to obtain an in-vehicle cable capable of transmitting signals in the high-frequency band of 4 GHz or higher.

[0015] (2) The first metal foil included in the first shield layer and the comprehensive shield layer may be in contact with each other.

[0016] By the first metal foil included in the first shield layer being in contact with the comprehensive shield layer, the first shield layer can be easily connected to an external terminal or the like, for example, via the comprehensive shield layer.

[0017] (3) Having a plurality of the two-core cables, the plurality of two-core cables are twisted together, and a second shield layer including a second metal foil is disposed on the outer periphery of the plurality of twisted two-core cables, the comprehensive shield layer and the outer jacket may be disposed so as to cover the outer periphery of the second shield layer.

[0018] By having a plurality of two-core cables, the types of devices that can be supported can be increased.

[0019] In addition, by disposing a second shield layer on the outer periphery of the two-core cable, an electrical connection can be formed between the first shield layer and the comprehensive shield layer.

[0020] (4) The second shield layer includes a double-sided metal tape having the second metal foil on the upper and lower surfaces of a base material, which is spirally wound along the longitudinal direction of the plurality of two-core cables, and the second metal foil provided on the upper surface of the base material and the comprehensive shield layer may be in contact with each other.

[0021] By spirally winding a double-sided metal tape having metal foils on the upper and lower surfaces of a base material along the longitudinal direction of a plurality of two-core cables, the metal foils arranged on the upper and lower surfaces of the base material are in contact with each other at the overlapping portions, and the two members can be electrically connected. Then, by the metal foil arranged on the upper surface of the base material being in contact with the comprehensive shielding layer, an electrical connection can be formed between the first shielding layer of the two-core cable and the comprehensive shielding layer via the second shielding layer. By electrically connecting the first shielding layer, the second shielding layer, and the comprehensive shielding layer, the first shielding layer and the second shielding layer can be easily connected to an external terminal or the like via the comprehensive shielding layer. Further, signal leakage to the outside and radio wave intrusion from the outside can be suppressed by the first shielding layer, the second shielding layer, and the comprehensive shielding layer.

[0022] (5) The second metal foil may be copper or aluminum.

[0023] By making the second metal foil of the second shielding layer copper or aluminum, a metal foil having uniform and sufficient conductivity can be obtained, and signal leakage to the outside and radio wave intrusion from the outside can be particularly suppressed.

[0024] (6) The insulating layer may include one or more selected from polypropylene and crosslinked polyethylene.

[0025] Since polypropylene and crosslinked polyethylene have excellent heat resistance, by including one or more selected from polypropylene and crosslinked polyethylene in the insulating layer, the heat resistance of the insulating layer and the in-vehicle cable including the insulating layer can be enhanced.

[0026] (7) The first metal foil may be copper or aluminum.

[0027] By making the first metal foil of the first shielding layer copper or aluminum, a metal foil having uniform and sufficient conductivity can be obtained, and signal leakage to the outside and radio wave intrusion from the outside can be particularly suppressed.

[0028] (8) The two-core cable has an insulating tape layer between the insulating layer and the first shield layer. The insulating tape layer may include an insulating tape provided with an insulating base material layer containing polyethylene terephthalate, which is spirally wound along the longitudinal direction of the insulating layer.

[0029] Polyethylene terephthalate has a higher dielectric constant compared to polypropylene, polyethylene, etc. Therefore, when setting the characteristic impedance of the in-vehicle cable to a desired value, by providing an insulating tape layer containing polyethylene terephthalate, the size of the insulating layer can be made smaller compared to the case where no insulating tape layer is provided. Accordingly, the size of the in-vehicle cable can also be made smaller, and the handleability of the in-vehicle cable can be improved.

[0030] (9) The thickness of the outer sheath may be 0.3 mm or more and 1.0 mm or less.

[0031] By setting the thickness of the outer sheath to 0.3 mm or more and 1.0 mm or less, the abrasion resistance, flammability, and flexibility of the in-vehicle cable can be particularly enhanced.

[0032] (10) The thickness of the outer sheath may be 0.4 mm or more and 0.8 mm or less.

[0033] By setting the thickness of the outer sheath to 0.4 mm or more and 0.8 mm or less, the abrasion resistance, flammability, and flexibility of the in-vehicle cable can be particularly enhanced.

[0034] [Details of Embodiments of the Present Disclosure] A specific example of an in-vehicle cable according to an embodiment of the present disclosure (hereinafter referred to as "the present embodiment") will be described below with reference to the drawings. It should be noted that the present invention is not limited to these examples, and is indicated by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims. [In-Vehicle Cable] (1) First Embodiment FIG. 1 shows a cross-sectional view of the in-vehicle cable 10 according to the present embodiment in a plane perpendicular to the longitudinal direction thereof. In FIG. 1, the X-axis direction is the height direction of the in-vehicle cable 10, the Y-axis direction is the width direction of the in-vehicle cable 10, and the Z-axis direction perpendicular to the paper surface is the longitudinal direction of the in-vehicle cable 10.

[0035] The inventor of the present invention has studied an in-vehicle cable capable of transmitting a signal of 4 GHz or higher, that is, suppressing the insertion loss for a signal in a high-frequency band of 4 GHz or higher. Then, by using a two-core cable having an insulating layer that collectively coats two conductors for transmitting signals, it has been found that an in-vehicle cable capable of suppressing the insertion loss of a signal in a high-frequency region of 4 GHz or higher can be obtained, and the present invention has been completed.

[0036] Therefore, the in-vehicle cable of the present embodiment relates to an in-vehicle cable capable of transmitting a signal of 4 GHz or higher.

[0037] Each member of the in-vehicle cable of the present embodiment will be described below. (1-1) Two-core cable As shown in FIG. 1, the in-vehicle cable 10 of the present embodiment includes a two-core cable 101 having a conductor 11 which is two twisted wires arranged in parallel, an insulating layer 12 that collectively coats the two conductors 11, and a first shield layer 14 including a first metal foil disposed on the outer periphery of the insulating layer 12. The members of the two-core cable 101 will be described below. (1-1-1) Conductor The in-vehicle cable of the present embodiment can have conductors which are two twisted wires arranged in parallel.

[0038] From the viewpoint of improving workability when wiring for attachment to a vehicle, the in-vehicle cable is required to have flexibility that allows it to be easily bent according to the shape of the attachment position of the in-vehicle cable. In addition, a force is applied to the in-vehicle cable according to the movement of connected members or the like, and it may be repeatedly bent, and bendability that makes it difficult to break when repeatedly bent is also required.

[0039] Therefore, as shown in FIG. 1, as the conductor 11 for transmitting signals, a stranded wire can be used in the in-vehicle cable 10 of the present embodiment. By using a stranded wire as the conductor 11, the flexibility that allows the in-vehicle cable to be easily bent and the bendability that makes it less likely to break when repeatedly bent can be enhanced compared to the case of a single wire where the conductor 11 is not a stranded wire.

[0040] The configuration such as the strand diameter D111 of the strands 111 constituting the stranded wire of the conductor 11 and the number thereof is not particularly limited, and can be selected according to the type of signal transmitted by the in-vehicle cable 10 and the degree of flexibility required for the in-vehicle cable 10. (Strand diameter D111) The strand diameter D111 of the strands constituting the stranded wire which is the conductor 11 is preferably, for example, 0.100 mm or more and 0.500 mm or less, and more preferably 0.110 mm or more and 0.220 mm or less. By setting the strand diameter D111 to 0.100 mm or more, the productivity of the stranded wire which is the conductor 11 can be enhanced while suppressing the number of strands constituting the stranded wire which is the conductor 11. Further, by setting the strand diameter D111 of the strands constituting the stranded wire which is the conductor 11 to 0.500 mm or less, the flexibility and bendability of the conductor 11 and the in-vehicle cable 10 including the conductor 11 can be enhanced.

[0041] The strand diameter of the strand can be measured and calculated by the following procedure.

[0042] First, in an arbitrary cross section perpendicular to the longitudinal direction of the strand, the strand diameter of the strand to be evaluated is measured with a micrometer along two orthogonal diameters of the strand. Then, the average of the measured values at the above two locations can be taken as the strand diameter of the strand. In this specification, the strand diameter of the strand can be measured and calculated in the same manner. (Number of strands) The number of strands constituting the stranded wire that is the conductor 11 is not particularly limited, and for example, it is preferably 7 or more and 37 or less, and more preferably 7 or more and 19 or less. By setting the number of strands constituting the stranded wire that is the conductor 11 to 7 or more, the flexibility and bendability of the conductor 11 and the in-vehicle cable 10 including the conductor 11 can be enhanced. Further, by setting the number of strands constituting the stranded wire that is the conductor 11 to 37 or less, the productivity of the stranded wire that is the conductor 11 can be enhanced. The number of strands constituting the stranded wire that is the conductor 11 means the number of strands each of the conductors 11, that is, the conductor 11A and the conductor 11B has.

[0043] The conductor 11A and the conductor 11B can, for example, have the strands with the above-described strand diameter D111 and can be configured by twisting the strands spirally along the longitudinal direction. It is preferable that the configurations, that is, the strands used and the number of strands are the same for the conductor 11A and the conductor 11B. As a specific configuration example of the conductor 11A and the conductor 11B, a stranded wire formed by twisting 7 strands of strands having a strand diameter of 0.2 mm can be exemplified. (Distance L11) The distance L11 between the conductor 11A and the conductor 11B is not particularly limited, but it is preferably 0.5 mm or more and 3.0 mm or less, and more preferably 0.8 mm or more and 2.0 mm or less. By setting the distance L11 between the conductor 11A and the conductor 11B to 0.5 mm or more, a sufficient distance can be ensured between the conductor 11A and the conductor 11B, and electrical contact, that is, the occurrence of a short circuit can be surely prevented. Further, by setting the distance L11 between the conductor 11A and the conductor 11B to 3.0 mm or less, the size of the in-vehicle cable 10 can be suppressed and the flexibility of the in-vehicle cable 10 can be enhanced.

[0044] The distance L11 between the conductor 11A and the conductor 11B means the distance between the center of the conductor 11A and the center of the conductor 11B in a cross section perpendicular to the longitudinal direction of the in-vehicle cable 10. The center of the conductor 11A and the center of the conductor 11B mean the centers of the circumscribed circles of the respective conductors in a cross section perpendicular to the longitudinal direction of the in-vehicle cable 10.

[0045] The distance L11 between the conductors can be a value measured at an arbitrary cross-section perpendicular to the longitudinal direction of the in-vehicle cable 10, for example. However, since the distance L11 between the conductors of the in-vehicle cable 10 may include a certain variation, it is preferable that the above distance L11 be the average value of the values measured at a plurality of cross-sections perpendicular to the longitudinal direction of the in-vehicle cable 10. The distance L11 between the conductors is preferably measured at 3 or more and 10 or less cross-sections perpendicular to the longitudinal direction of the in-vehicle cable 10, particularly 3 cross-sections from the viewpoint of efficiency, and the average value thereof is taken. When measuring the distance L11 between the conductors at a plurality of cross-sections perpendicular to the longitudinal direction of the in-vehicle cable 10, the distance between adjacent measurement surfaces along the longitudinal direction of the in-vehicle cable 10 is preferably 10 mm or more and 50 mm or less, and can be, for example, 20 mm.

[0046] As a specific configuration example of the distance L11 between the conductor 11A and the conductor 11B, 1.8 mm can be exemplified.

[0047] The conductors 11A and 11B can be arranged in parallel as described above. The distance L11 between the conductors 11A and 11B is preferably constant, but even in this case, the distance L11 between the conductor 11A and the conductor 11B can be within a range that can be regarded as constant including manufacturing tolerances. (Regarding the material of the conductor) The material of the conductor 11 is not particularly limited, and for example, one or more conductor materials selected from copper, soft copper, silver, nickel-plated soft copper, tin-plated soft copper, etc. can be used. (1-1-2) Insulation layer The in-vehicle cable 10 of the present embodiment can have an insulation layer 12 that collectively covers the two conductors 11.

[0048] Conventionally, in a two-core cable called a twinax cable or the like, each conductor was coated with an insulating layer, and the two coated electric wires were not coated with a shield layer or an outer sheath. However, when each conductor is coated with an insulating layer, variations may occur in the thickness of the insulating layer or the like during manufacturing, or the shield layer may fall into the recess between the two coated electric wires, making it difficult to keep the environment of materials between the two conductors constant. For this reason, for example, in a high-frequency band of 4 GHz or higher, it was difficult to sufficiently suppress the insertion loss of a signal and to make a cable capable of transmitting a signal of 4 GHz or higher.

[0049] On the other hand, in the in-vehicle cable of the present embodiment, since the two conductors 11 are coated together, the environment of the material between the two conductors 11 can be easily made constant. For this reason, it is possible to sufficiently suppress the insertion loss of a signal in a high-frequency band of 4 GHz or higher and to make an in-vehicle cable capable of transmitting a signal in a high-frequency band of 4 GHz or higher.

[0050] Note that the in-vehicle cable 10 of the present embodiment only needs to be able to transmit a signal in a high-frequency region of 4 GHz or higher, and the upper limit value of the frequency band of the signal to be transmitted is not particularly limited. For example, it is preferable that the in-vehicle cable 10 can transmit a signal in a high-frequency band of 4 GHz or higher and 30 GHz or lower. (Size of the insulating layer) The size of the insulating layer 12 is not particularly limited. However, in a cross-section perpendicular to the longitudinal direction of the in-vehicle cable 10, the width W121 corresponding to the major axis length of the insulating layer 12 is preferably 1.5 mm or more and 9.0 mm or less, and more preferably 1.5 mm or more and 4.0 mm or less.

[0051] By setting the width W121 to 1.5 mm or more, while ensuring a sufficient distance between the conductors 11, the surface of the conductor 11 can be coated with the insulating layer 12 having a sufficient thickness to protect the conductor 11. Also, by setting the width W121 to 9.0 mm or less, the size of the in-vehicle cable 10 can be suppressed, and the handleability can be improved.

[0052] Also, the height H12 corresponding to the minor axis length of the insulating layer 12 is preferably 0.75 mm or more and 4.5 mm or less, and more preferably 0.8 mm or more and 3.5 mm or less.

[0053] By setting the height H12 of the insulating layer 12 to 0.75 mm or more, the surface of the conductor 11 can be covered with the insulating layer 12 of sufficient thickness to protect the conductor 11. Also, by setting the height H12 of the insulating layer 12 to 4.5 mm or less, the size of the in-vehicle cable 10 can be suppressed, and in particular, the flexibility can be enhanced.

[0054] The insulating layer 12 can also have a flat portion 122 along the width direction, that is, the Y-axis direction, in a cross section perpendicular to the longitudinal direction of the in-vehicle cable 10. The width W122 of the flat portion 122 is not particularly limited, but is preferably, for example, 0.5 mm or more and 3.0 mm or less, and more preferably 0.8 mm or more and 2.5 mm or less.

[0055] The in-vehicle cable 10 can be bent easily, for example, along the X-axis direction. By setting the width W122 of the flat portion 122 to 0.5 mm or more, the in-vehicle cable 10 can be bent particularly easily. That is, the flexibility of the in-vehicle cable 10 can be enhanced.

[0056] Also, by setting the width W122 of the flat portion 122 to 3.0 mm or less, the size of the in-vehicle cable 10 can be suppressed, and the handleability can be enhanced.

[0057] The length of each part of the insulating layer 12 is not particularly limited, and the length of each part can be selected within the above range as described above. For example, 3.7 mm can be exemplified as the width W121, 1.8 mm can be exemplified as the height H12, and 1.8 mm can be exemplified as the width W122 of the flat portion 122 as representative values.

[0058] The lengths of the respective parts of the insulating layer 12, i.e., the width W121, the width W122 of the flat part, and the height H12, can be values measured in any cross-section perpendicular to the longitudinal direction of the in-vehicle cable 10, for example. However, since the lengths of the respective parts of the insulating layer 12 of the in-vehicle cable 10 may include a certain variation, it is preferable that they be the average values of the values measured in a plurality of cross-sections perpendicular to the longitudinal direction of the in-vehicle cable 10. The above width W121, the width W122 of the flat part, and the height H12 are preferably measured in 3 to 10 cross-sections perpendicular to the longitudinal direction of the in-vehicle cable 10, particularly 3 cross-sections from the viewpoint of efficiency, and the lengths of the respective parts are measured and taken as the average values. When measuring the lengths of the respective parts in a plurality of cross-sections perpendicular to the longitudinal direction of the in-vehicle cable 10, the distance between adjacent measurement surfaces along the longitudinal direction of the in-vehicle cable 10 is preferably 10 mm or more and 50 mm or less, and can be, for example, 20 mm. (Material of the insulating layer) The material of the insulating layer 12 is not particularly limited and can be selected according to the characteristics required for the in-vehicle cable 10, etc.

[0059] The insulating layer 12 can contain, for example, an insulating resin, and the insulating resin is not particularly limited, but it is preferably one or more selected from, for example, polypropylene and crosslinked polyethylene. That is, the insulating layer 12 preferably contains one or more selected from polypropylene and crosslinked polyethylene.

[0060] Since polypropylene and crosslinked polyethylene are excellent in heat resistance, by including one or more selected from polypropylene and crosslinked polyethylene as the insulating resin in the insulating layer 12, the heat resistance of the insulating layer 12 and the in-vehicle cable 10 including the insulating layer 12 can be enhanced.

[0061] Note that since it is usually difficult to crosslink polypropylene, uncrosslinked, non-crosslinked polypropylene can be preferably used.

[0062] In addition to the above-mentioned insulating resin, the insulating layer 12 can also contain various additives. The insulating layer 12 can contain, as additives, for example, one or more selected from flame retardants, antioxidants, crosslinking agents, crosslinking aids, lubricants, and the like.

[0063] As the flame retardant, antioxidant, crosslinking agent, etc., known materials can be used and are not particularly limited.

[0064] As the flame retardant, for example, halogen-based flame retardants or non-halogen-based flame retardants can be used. As the halogen-based flame retardant, bromine-based flame retardants and the like can be used. As the non-halogen-based flame retardant, metal hydroxides such as magnesium hydroxide, nitrogen-based flame retardants, antimony trioxide, red phosphorus, phosphorus-based flame retardants such as phosphate esters, and the like can be used.

[0065] The method for forming the insulating layer 12 is not particularly limited, but the material contained in the insulating layer can be formed on the outer periphery of the conductor 11 by extrusion molding.

[0066] In the insulating layer 12, in addition to the above-mentioned conductor 11, a drain wire or the like can be provided, but it is preferable that the in-vehicle cable of the present embodiment does not include a drain wire or the like in the insulating layer 12. Since the drain wire is electrically connected to a shield layer or the like, it is usually used without a coating. Therefore, if a drain wire is arranged in the insulating layer 12, there is a risk that the conductor 11 and the drain wire will come into contact and cause a short circuit. On the other hand, by not arranging a drain wire in the insulating layer 12, an electrical connection, that is, a short circuit, between the conductor 11 and the drain wire can be prevented.

[0067] In particular, in the in-vehicle cable 10 of the present embodiment, it is preferable that the wire in the insulating layer 12 is only the conductor 11. (1-1-3) First shield layer The in-vehicle cable 10 can have a first shield layer 14 including a first metal foil arranged on the outer periphery of the insulating layer 12.

[0068] Since the vehicle-mounted cable 10 has the first shield layer 14, it is possible to prevent signal leakage to the outside and radio wave intrusion from the outside, that is, to exhibit a shielding effect.

[0069] Further, it is preferable that the first metal foil included in the first shield layer is in contact with the comprehensive shield layer 15 described later. Since the first metal foil included in the first shield layer 14 is in contact with the comprehensive shield layer 15, the first shield layer 14 can be easily connected to an external terminal or the like, for example, via the comprehensive shield layer 15.

[0070] The configuration of the first shield layer 14 is not particularly limited. For example, it may include a metal tape having a metal foil wound spirally along the longitudinal direction of the insulating layer 12 on the outer periphery of the insulating layer 12 or the insulating tape layer 13 described later. The first shield layer 14 can also be composed of the above metal tape. In this case, the metal foil included in the metal tape becomes the first metal foil.

[0071] As described above, when the first shield layer 14 contains a metal tape, the configuration of the metal tape is not particularly limited, but the metal tape preferably has a metal foil on at least one surface of the base material.

[0072] The metal tape used when forming the first shield layer 14 can have, for example, a configuration of the metal tape 141 shown in FIG. 4A in a cross section perpendicular to the longitudinal direction.

[0073] The metal tape 141 shown in FIG. 4A has a structure in which a base material 1411 and a metal foil 1412 are laminated. Therefore, by winding the metal tape 141 spirally along the longitudinal direction of the insulating layer 12 or the like on the outer periphery of the insulating layer 12 or the like, the first shield layer 14 including the first metal foil can be formed. In order to form the first shield layer 14 on the entire outer periphery of the insulating layer 12, it is preferable to wind the metal tape 141 around the outer periphery of the insulating layer 12 or the like so that a part thereof overlaps with each other.

[0074] The metal tape 141 may also have an adhesive layer 1413 on the surface of the base material 1411 on the side where the metal foil 1412 is not provided. When the metal tape 141 has the adhesive layer 1413, when the metal tape 141 is spirally wound along the longitudinal direction of the insulating layer 12 around the outer periphery of the insulating layer 12 or the like, the metal tapes 141 can be adhered to each other through the adhesive layer 1413 at the overlapping portions of the metal tapes 141. Therefore, the shape of the first shield layer 14 can be stabilized.

[0075] When forming the first shield layer 14 using the metal tape 141, it is preferable to wind it around the outer periphery of the insulating layer 12 or the like so that the surface 141B on the metal foil 1412 side is positioned on the side of the comprehensive shield layer 15 so that the metal foil 1412 can come into contact with the comprehensive shield layer 15 or the like and be electrically connected. In this case, the surface 141A on the base material 1411 side will be positioned on the side of the insulating layer 12.

[0076] The metal tape used when forming the first shield layer 14 is not limited to the metal tape 141. The metal tape used when forming the first shield layer 14 may be a double-sided metal tape such as the double-sided metal tape 142 shown in FIG. 4B, which has an upper metal foil 1422 and a lower metal foil 1423 on both sides, that is, on the upper and lower surfaces of the base material 1421.

[0077] Even in the case of the double-sided metal tape 142 shown in FIG. 4B, an adhesive layer can be provided on either one or both of the surfaces 142A and 142B of the upper metal foil 1422 and the lower metal foil 1423.

[0078] The size of the metal tape used when forming the first shielding layer 14 is not particularly limited. For example, when using the metal tape 141 shown in FIG. 4A, the total thickness of the metal foil and the base material, that is, the thickness T141 in FIG. 4A is preferably, for example, 5 μm or more and 30 μm or less, and more preferably 10 μm or more and 30 μm or less. In the metal tape 141 shown in FIG. 4A, by setting the total thickness of the metal foil and the base material to 5 μm or more, a sufficient thickness can be ensured for the metal foil, and the shielding effect can be enhanced. Also, by setting the total thickness of the metal foil and the base material to 30 μm or less, when winding the metal tape around the outer periphery of the insulating layer 12 or the like, it becomes easier to make the metal tape follow the outer shape of the insulating layer 12 or the like. For this reason, regardless of the position in the longitudinal direction of the in-vehicle cable, the shape of the first shielding layer 14 can be made constant, and the signal transmission performance of the in-vehicle cable can be made particularly stable.

[0079] When forming the first shielding layer 14, when using the double-sided metal tape 142 shown in FIG. 4B, the total thickness of the metal foil and the base material, that is, the thickness T142 is preferably 10 μm or more and 100 μm or less. More preferably, it is 15 μm or more and 80 μm or less. By setting the total thickness of the metal foil and the base material to 10 μm or more, a sufficient thickness can be ensured for each metal foil, and the shielding effect can be enhanced. Also, by setting the total thickness of the metal foil and the base material to 100 μm or less, when winding the metal tape around the outer periphery of the insulating layer 12 or the like, it becomes easier to make the metal tape follow the outer shape of the insulating layer 12 or the like. For this reason, regardless of the position in the longitudinal direction of the in-vehicle cable, the shape of the first shielding layer 14 can be made constant, and the signal transmission performance of the in-vehicle cable can be made particularly stable.

[0080] The thickness T141 and the thickness T142 are not particularly limited, and the thickness can be selected, for example, within the above range as described above. For example, 15 μm can be exemplified as a representative value for the thickness T141, and 20 μm can be exemplified as a representative value for the thickness T142.

[0081] The thickness T1413 of the adhesive layer 1413 is not particularly limited either. For example, it is preferably 0.1 μm or more and 10 μm or less, and more preferably 0.1 μm or more and 5 μm or less. By setting the thickness T1413 of the adhesive layer 1413 to 0.1 μm or more, a sufficient amount of adhesive can be contained, and the shape of the first shield layer 14 can be made particularly stable. Since there is no difference in effect even if the adhesive layer 1413 is made excessively thick, it is preferably 10 μm or less from the viewpoints of cost and the like as described above. The thickness T1413 of the adhesive layer 1413 is not particularly limited, and the thickness can be selected within the above range, for example, as described above. For example, 2 μm can be exemplified as a typical value for the thickness T1413.

[0082] The material of the first metal foil of the first shield layer 14 may be any conductive material from the viewpoint of exhibiting a shielding effect, and is not particularly limited. For example, it is preferable that the first metal foil is copper or aluminum. By using copper or aluminum as the first metal foil of the first shield layer 14, a metal foil having uniform and sufficient conductivity can be obtained, and signal leakage to the outside and radio wave intrusion from the outside can be particularly suppressed.

[0083] The materials of the base material 1411 of the metal tape 141 and the base material 1421 of the double-sided metal tape 142 are not particularly limited. For example, polyethylene terephthalate (PET) can be used as the material of the base material. (1-1-4) Insulating tape layer The two-core cable 101 can also have an insulating tape layer 13 between the insulating layer 12 and the first shield layer 14 described above.

[0084] The insulating tape layer 13 can include the insulating tape 130 shown in FIG. 3, which is spirally wound along the longitudinal direction of the insulating layer 12. Note that the insulating tape layer 13 can also be composed of the insulating tape 130.

[0085] FIG. 3 shows a cross-sectional view of the insulating tape 130 in the thickness direction. The insulating tape 130 can have an insulating base layer 131 containing polyethylene terephthalate (PET). The insulating base layer 131 can also be composed of polyethylene terephthalate.

[0086] Polyethylene terephthalate has a higher dielectric constant compared to polypropylene, polyethylene, etc. Therefore, when setting the characteristic impedance of the in-vehicle cable 10 to a desired value, by providing the insulating tape layer 13 containing polyethylene terephthalate, the size of the insulating layer 12 can be made smaller compared to the case where the insulating tape layer 13 is not provided. Accordingly, the size of the in-vehicle cable 10 can also be made smaller, improving the handleability of the in-vehicle cable 10.

[0087] The insulating tape 130 can also have an adhesive layer 132 on one of the upper and lower surfaces of the insulating base layer 131. By providing the adhesive layer 132, when the insulating tape 130 is spirally wound around the outer periphery of the insulating layer 12 along the longitudinal direction of the insulating layer 12, the insulating tapes 130 can be adhered to each other through the adhesive layer 132 at the overlapping portions of the insulating tapes 130. Therefore, the shape of the insulating tape layer 13 can be stabilized.

[0088] When winding the insulating tape 130 having the adhesive layer 132 around the outer periphery of the insulating layer 12, it is preferably arranged such that the surface 13B provided with the adhesive layer 132 is located on the side of the aforementioned first shield layer 14. That is, in the above case, the insulating tape 130 is preferably arranged such that the surface 13A not provided with the adhesive layer 132 is located on the side of the insulating layer 12.

[0089] By arranging the surface 13A not provided with the adhesive layer 132 on the side of the insulating layer 12, it is possible to prevent the insulating layer 12 and the insulating tape layer 13, etc. from being adhered by the adhesive layer 132. Therefore, at the longitudinal end of the in-vehicle cable 10, for connection to equipment, etc., the operation of removing the outer cover 16, etc. and taking out the conductor 11 can be easily carried out.

[0090] The thickness T131 of the insulating base material layer 131 of the insulating tape 130 is not particularly limited, but for example, it is preferably 5 μm or more and 80 μm or less, and more preferably 5 μm or more and 20 μm or less.

[0091] By setting the thickness of the insulating base material layer 131 to 5 μm or more, the thickness of the insulating tape layer, which is a layer containing polyethylene terephthalate with a high dielectric constant, can be made sufficiently thick, and the core by the insulating layer 12 can be made smaller. As a result, the size of the in-vehicle cable 10 can also be suppressed, and the flexibility can be enhanced.

[0092] By setting the thickness of the insulating base material layer 131 to 80 μm or less, the size of the in-vehicle cable 10 can be suppressed, and the flexibility can be enhanced.

[0093] When the insulating tape 130 has an adhesive layer 132, the thickness T132 thereof is not particularly limited, but for example, it is preferably 0.1 μm or more and 10 μm or less, and more preferably 0.1 μm or more and 5 μm or less.

[0094] By setting the thickness T132 of the adhesive layer 132 to 0.1 μm or more, a sufficient amount of adhesive can be contained, and the shape of the insulating tape layer 13 can be made particularly stable. Since there is no difference in effect even if the adhesive layer 132 is made excessively thick, it is preferably 10 μm or less from the viewpoint of cost and the like as described above.

[0095] The thickness T131 of the insulating base material layer 131 and the thickness T132 of the adhesive layer 132 can be arbitrarily selected from the above ranges, for example. For example, 12 μm can be exemplified as the thickness T131 of the insulating base material layer 131, and 2 μm can be exemplified as the thickness T132 of the adhesive layer 132. (1-2) Comprehensive shield layer The in-vehicle cable 10 of the present embodiment can have a comprehensive shield layer 15 having a braided structure disposed on the outer periphery of the two-core cable 101.

[0096] The comprehensive shield layer 15 can be formed by arranging metal wires in a braided structure as described above. The material of the metal wires of the comprehensive shield layer 15 is not particularly limited, and for example, copper, aluminum, copper alloys, etc. can be used. The metal wires of the comprehensive shield layer 15 may be subjected to a plating treatment of silver or tin on the surface. Therefore, as the metal wires of the comprehensive shield layer 15, for example, silver-plated copper alloys, tin-plated copper alloys, etc. can also be used.

[0097] As described above, it is preferable that the comprehensive shield layer 15 is in contact with and electrically connected to the first metal foil of the first shield layer 14 described above. In this case, the first shield layer 14 can be easily connected to an external terminal or the like, for example, via the comprehensive shield layer 15.

[0098] By providing the comprehensive shield layer 15, together with the first shield layer 14 described above, it is possible to reduce the intrusion of external noise and signal leakage to the outside. Also, by providing an electrical connection between the comprehensive shield layer 15 and the first shield layer 14 described above, the first shield layer 14 can be easily connected to an external terminal or the like via the comprehensive shield layer 15.

[0099] The thickness T15 of the comprehensive shield layer 15 is not particularly limited, but it is preferably, for example, 0.1 mm or more and 0.5 mm or less, and more preferably 0.1 mm or more and 0.3 mm or less.

[0100] By setting the thickness T15 of the comprehensive shield layer 15 to 0.1 mm or more, it is possible to particularly reduce the intrusion of external noise and signal leakage to the outside. Also, by setting the thickness T15 of the comprehensive shield layer 15 to 0.5 mm or less, the flexibility of the in-vehicle cable 10 can be enhanced.

[0101] The thickness T15 of the comprehensive shield layer 15 can be arbitrarily selected from the above range, for example. For example, 0.2 mm can be exemplified as a representative value for the thickness T15 of the comprehensive shield layer 15.

[0102] The thickness T15 of the comprehensive shield layer 15 can be measured and calculated, for example, according to the following procedure.

[0103] In any cross-section perpendicular to the longitudinal direction of the in-vehicle cable 10, measure the thickness of the comprehensive shield layer 15 with a micrometer at one location along the width direction of the in-vehicle cable 10 and one location along the height direction, for a total of two locations. Note that the width direction is the Y-axis direction in FIG. 1 and can also be referred to as the longitudinal direction. Also, the thickness direction is the X-axis direction in FIG. 1 and can also be referred to as the short-side direction.

[0104] And the average value of the measured values at the two measured locations can be taken as the thickness T15 of the comprehensive shield layer 15.

[0105] The thickness T15 of the comprehensive shield layer 15 can be taken as the value measured in any cross-section perpendicular to the longitudinal direction of the in-vehicle cable 10 as described above. However, since the thickness T15 of the comprehensive shield layer 15 may include a certain variation, it is preferably the average value of the values measured in a plurality of cross-sections perpendicular to the longitudinal direction of the in-vehicle cable 10. For example, it is preferable to measure the thickness T15 of the comprehensive shield layer 15 at 3 to 10 cross-sections perpendicular to the longitudinal direction of the in-vehicle cable 10, particularly 3 cross-sections from the perspective of efficiency, and take the average value. When measuring the length of each part at a plurality of cross-sections perpendicular to the longitudinal direction of the in-vehicle cable 10, the distance between adjacent measurement surfaces along the longitudinal direction of the in-vehicle cable 10 is preferably 10 mm or more and 50 mm or less, and can be, for example, 20 mm.

[0106] The thickness T16 of the following outer sheath 16 can be measured in the same manner. (1-3) Outer Sheath The in-vehicle cable of this embodiment can have an outer sheath 16 disposed on the outer periphery of the comprehensive shield layer 15. By providing the outer sheath 16, the two-core cable 101 disposed inside, the comprehensive shield layer 15, etc. can be protected.

[0107] The material of the outer sheath 16 is not particularly limited, and for example, it can contain one or more resins selected from polyolefin resins such as polyethylene and polypropylene, and resins such as polyvinyl chloride. The resin of the outer sheath 16 may or may not be cross-linked.

[0108] In addition to the above resins, the outer sheath 16 can also contain additives such as flame retardants, flame retardant aids, antioxidants, lubricants, colorants, reflection imparting agents, concealing agents, processing stabilizers, and plasticizers.

[0109] The method for forming the outer sheath 16 is not particularly limited, and for example, it can be formed by full extrusion molding or draw-down extrusion molding using the materials contained in the outer sheath 16.

[0110] The thickness T16 of the outer sheath 16 is not particularly limited, but for example, it is preferably 0.2 mm or more and 1.2 mm or less, more preferably 0.3 mm or more and 1.0 mm or less, and even more preferably 0.4 mm or more and 0.8 mm or less.

[0111] By setting the thickness T16 of the outer sheath 16 to 0.2 mm or more, the internal two-core cable 101, the comprehensive shield layer 15, etc. can be sufficiently protected. Also, by setting the thickness T16 of the outer sheath 16 to 1.2 mm or less, the size of the in-vehicle cable 10 can be suppressed and the flexibility can be enhanced.

[0112] Moreover, by setting the thickness T16 of the outer sheath 16 to 0.3 mm or more and 1.0 mm or less, particularly 0.4 mm or more and 0.8 mm or less, the abrasion resistance, flammability, and flexibility of the in-vehicle cable 10 of this embodiment can be particularly enhanced.

[0113] The thickness T16 of the outer sheath 16 can be arbitrarily selected from the above range, for example, 0.5 mm can be exemplified as a representative value for the thickness T16 of the outer sheath 16.

[0114] Since the thickness T16 of the outer sheath 16 can be measured in the same manner as the thickness T15 of the comprehensive shield layer 15, the description is omitted here. (2) Second Embodiment The in-vehicle cable of this embodiment can also include a plurality of two-core cables according to the devices to be connected and the like.

[0115] Therefore, as shown in FIG. 2, the in-vehicle cable 20 of this embodiment can have a plurality of two-core cables 101. In this case, the plurality of two-core cables 101 can be twisted together, and a second shield layer 24 including a second metal foil can be arranged on the outer periphery of the plurality of twisted two-core cables 101.

[0116] Then, the above-described comprehensive shield layer 15 and outer jacket 16 can be arranged so as to cover the outer periphery of the second shield layer 24.

[0117] By having a plurality of two-core cables 101 as described above, the in-vehicle cable 20 of this embodiment can increase the types of devices that can be supported.

[0118] Regarding matters described in the first embodiment, such as the two-core cable 101, some explanations will be omitted. Hereinafter, each member included in the in-vehicle cable 20 of this embodiment will be described. (2-1) Two-core cable The in-vehicle cable 20 shown in FIG. 2 has two two-core cables 101. However, the in-vehicle cable of this embodiment can also have three or more two-core cables.

[0119] The plurality of two-core cables 101 can be spirally twisted together along the longitudinal direction. At this time, the twist pitch is not limited because it can be selected according to the size of the twisted unit, but it is preferably, for example, 100 mm or more and 300 mm or less. Each of the two-core cables 101 has a conductor 11 which is a pair of twisted wires arranged in parallel as described above, an insulating layer 12 that collectively coats the two conductors 11, and a first shield layer 14 arranged on the outer periphery of the insulating layer 12. An insulating tape layer 13 can also be provided between the first shield layer 14 and the insulating layer 12.

[0120] Since the two-core cable 101 has already been described, the description thereof will be omitted here. (2-2) Second shielding layer The second shielding layer 24 can be disposed on the outer periphery of a plurality of twisted two-core cables 101 and can be disposed so as to be in contact with the outer periphery (outer surface) of the two-core cable 101. By disposing the second shielding layer on the outer periphery of the two-core cable, an electrical connection can be formed between the first shielding layer 14 and the comprehensive shielding layer 15.

[0121] The second shielding layer 24 can include a second metal foil, and preferably includes a metal tape spirally wound along the longitudinal direction of a plurality of two-core cables 101, for example. In order to form the second shielding layer 24 so as to cover the entire plurality of two-core cables 101, it is preferable that the metal tape be wound around the outer periphery of the plurality of two-core cables 101 such that a part thereof overlaps with each other.

[0122] The metal tape included in the second shielding layer 24 is preferably a double-sided metal tape having an upper metal foil 1422 and a lower metal foil 1423 on the upper and lower surfaces, that is, both surfaces, of a base material 1421, such as the double-sided metal tape 142 shown in FIG. 4B. And it is preferable that the upper metal foil 1422, which is the metal foil disposed on the upper surface of the base material 1421, is in contact with the comprehensive shielding layer 15. Also, the lower metal foil 1423, which is the metal foil disposed on the lower surface of the base material 1421, is preferably in contact with the first metal foil of the first shielding layer 14. In this case, the upper metal foil 1422 and the lower metal foil 1423 become the second metal foil included in the second shielding layer 24.

[0123] A double-sided metal tape having metal foils on the upper and lower surfaces of a base material 1421 is spirally wound along the longitudinal direction of a plurality of two-core cables 101. In the overlapping portion, the upper metal foil 1422 and the lower metal foil 1423 are in contact with each other, and electrical connection between the two members can be achieved. And, by the upper metal foil 1422 disposed on the upper surface of the base material 1421 being in contact with the comprehensive shield layer 15, for example, an electrical connection can be formed between the first shield layer 14 of the two-core cable 101 and the comprehensive shield layer 15 via the second shield layer 24. By electrically connecting the first shield layer 14, the second shield layer 24, and the comprehensive shield layer 15 as described above, the first shield layer 14 and the second shield layer 24 can be easily connected to an external terminal or the like via the comprehensive shield layer 15. Further, the first shield layer 14, the second shield layer 24, and the comprehensive shield layer 15 can suppress signal leakage to the outside and radio wave intrusion from the outside.

[0124] The material of the second metal foil of the second shield layer 24 may be any conductive material from the viewpoint of exhibiting a shielding effect and is not particularly limited. However, for example, it is preferable that the second metal foil is copper or aluminum. By making the second metal foil of the second shield layer 24 copper or aluminum, a metal foil having uniform and sufficient conductivity can be obtained, and signal leakage to the outside and radio wave intrusion from the outside can be particularly suppressed.

[0125] Since the suitable thicknesses and the like of each part of the double-sided metal tape shown in FIG. 4B have already been described, the description is omitted here. (2-3) Comprehensive shield layer, outer sheath The comprehensive shield layer 15 and the outer sheath 16 can be configured in the same manner as in the case of the first embodiment, and thus the description is omitted here.

Example

[0126] Specific examples will be given below for explanation, but the present invention is not limited to these examples. [Experimental Example 1] An in-vehicle cable 10 having the cross-sectional structure shown in FIG. 1 (hereinafter also referred to as the cable of Configuration 1) and a cable 50 having the cross-sectional structure shown in FIG. 5 (hereinafter also referred to as the cable of Configuration 2) were prepared, and skew and insertion loss were evaluated.

[0127] The cable of Configuration 1 is an example, and the cable of Configuration 2 is a comparative example. (1) Regarding the configuration of the cable (Cable of Configuration 1) The in-vehicle cable 10 having the cross-sectional structure shown in FIG. 1 has the configuration of Configuration 1 shown in Table 1. Specifically, it has two conductors 11 formed by twisting seven strands of strand wires 111 made of tinned copper wire with a strand wire diameter D111 of 0.16 mm. The conductor diameter of the conductor 11 was 0.48 mm.

[0128]

Table 1

[0129] The strand wire diameter was measured by the following procedure. First, in an arbitrary cross-section perpendicular to the longitudinal direction of the strand wire, the strand wire diameter of the strand wire was measured with a micrometer along two diameters perpendicular to the strand wire. Then, the average of the measured values at the above two locations was taken as the strand wire diameter of the strand wire. The conductor diameter was measured and calculated in the same manner.

[0130] The two conductors 11 are arranged in parallel and are collectively covered by an insulating layer 12. Polypropylene is used as the material of the insulating layer 12, and cross-linking is not performed. The distance L11 between the conductors 11, the width W121 of the insulating layer 12, and the height H12 are as shown in Table 1. Note that the distance between the conductors 11 corresponds to the distance between the centers of the circumscribed circles of the respective conductors 11.

[0131] The distance L11 between the conductors 11, the width W121 of the insulating layer 12, and the height H12 were measured and calculated by the following procedure. The distance L11 between the conductors 11 will be described as an example.

[0132] In three cross-sections perpendicular to the longitudinal direction of the obtained in-vehicle cable, the distance L11 between the conductors 11 was measured, and the average value was taken as the distance L11 between the conductors 11 in the in-vehicle cable. The three measured cross-sections were set such that the distance along the longitudinal direction of the cable between adjacent cross-sections was 20 mm. The width W121 and height H12 of the insulating layer 12 were measured in the same manner.

[0133] An insulating tape layer 13, a first shield layer 14, a comprehensive shield layer 15, and an outer sheath 16 are arranged on the outer periphery of the insulating layer 12, and the thicknesses of each part are as shown in Table 1.

[0134] Since the insulating tape layer 13 was formed using the insulating tape 130 shown in FIG. 3, the thickness of the insulating tape layer is shown as the thickness T131 of the insulating base material layer 131 in Table 1. The insulating base material layer 131 is made of polyethylene terephthalate.

[0135] Since the first shield layer 14 was formed using the metal tape 141 shown in FIG. 4A, the total thickness T141 of the base material 1411 and the metal foil 1412 in the metal tape 141 is shown in Table 1. The base material 1411 is made of polyethylene terephthalate, and an aluminum foil is used as the metal foil 1412.

[0136] When forming the insulating tape layer 13 and the first shield layer 14, the insulating tape 130 and the metal tape 141 were spirally wound along the longitudinal direction of the insulating layer 12 so that the adhesive layer 132 of the insulating tape 130 and the adhesive layer 1413 of the metal tape 141 adhered. That is, the insulating tape 130 was wound so that the surface 13A was located on the insulating layer 12 side, and the metal tape 141 was wound so that the surface 141A was located on the insulating layer 12 side.

[0137] Tinned copper wire was used as the strand constituting the comprehensive shield layer 15. Polyethylene was used as the resin material of the outer sheath 16 and cross-linked.

[0138] The thickness T15 of the integrated shield layer 15 and the thickness T16 of the jacket 16 were measured and calculated according to the following procedure. Taking the case of the integrated shield layer 15 as an example, the description is as follows.

[0139] First, at three cross-sections perpendicular to the longitudinal direction of the obtained in-vehicle cable 10, the thickness T15 was measured with a micrometer at a total of two locations, one along the width direction and one along the height direction of the in-vehicle cable 10 respectively. The average of the measured values at the two measured locations was taken as the thickness T15 of the integrated shield layer 15 at the cross-section.

[0140] Next, the average value of the thickness T15 of the integrated shield layer 15 calculated individually for the three cross-sections was taken as the thickness T15 of the integrated shield layer 15 in the in-vehicle cable. The three measured cross-sections were set such that the distance along the longitudinal direction of the cable between adjacent cross-sections was 20 mm.

[0141] The thickness T16 of the jacket 16 was also measured and calculated in the same manner as the thickness T15 of the integrated shield layer 15. (Cable of Configuration 2) The cable 50 having the cross-sectional structure shown in FIG. 5 has the configuration of Configuration 2 shown in Table 1. Specifically, it has two conductors 51 formed by twisting seven strands of strand wires 511 which are tinned copper wires with a strand wire diameter D511 of 0.16 mm. The outer diameter of the conductor 51 was 0.48 mm.

[0142] The outer diameter of the strand wire and the outer diameter of the conductor were measured and evaluated in the same manner as in the case of the cable of Configuration 1.

[0143] Each conductor 51 is a covered wire 52A, 52B with an insulating layer 521 disposed on the outer periphery, and the two covered wires 52A, 52B are twisted together with a twist pitch of 12 mm. Cross-linked polyethylene was used for the insulating layers of the covered wires 52A, 52B.

[0144] The outer diameter D52 of the covered wire is 1.23 mm, and the distance L51 between the conductors 51 is 1.23 mm. The distance between the conductors 51 corresponds to the distance between the centers of the circumscribed circles of the respective conductors 51.

[0145] The outer diameter D52 of the coated wire was evaluated in the same manner as in the case of the strand diameter. The distance L51 between the conductors 51 was evaluated in the same manner as in the cable of Configuration 1.

[0146] An insulating tape layer 53, a first shield layer 54, a comprehensive shield layer 55, and an outer sheath 56 are disposed on the outer circumferences of the two coated wires 52A and 52B, and the thicknesses of the respective parts are as shown in Table 1.

[0147] The insulating tape layer 53 to the outer sheath 56 were configured in the same manner as in the case of the in-vehicle cable 10 of Configuration 1.

[0148] Regarding the insulating tape layer 53 to the outer sheath 56, the measurement and calculation methods of the lengths of the respective parts were carried out in the same manner as in the case of the cable of Configuration 1, and thus the description is omitted here. (2) Evaluation (Skew) Using a digital serial analyzer, an electrical pulse was sent to two conductors of the cable of Configuration 1 and the cable of Configuration 2, the delay time per meter was measured, and Skew was obtained. Twenty measurements were made for each cable having the same configuration.

[0149] In the case of the in-vehicle cable 10 of Configuration 1, it was confirmed that Skew is distributed in the range of 0 psec / m or more and 4 psec / m or less.

[0150] On the other hand, in the case of the cable 50 of Configuration 2, it was confirmed that Skew is distributed in the range of 0 psec / m or more and 15 psec / m or less.

[0151] That is, it was confirmed that the delay time of the in-vehicle cable 10 of Configuration 1 is suppressed as compared with the cable 50 of Configuration 2. (Insertion Loss) Differential signals were input to the cables of Configuration 1 and Configuration 2, and the frequency characteristics of the insertion loss were evaluated. The evaluation was performed at room temperature in the atmosphere. The results are shown in FIG. 7. In FIG. 7, line 71 represents the evaluation result for the cable of Configuration 1, and line 72 represents the evaluation result for the cable of Configuration 2.

[0152] As is clear from FIG. 7, it was confirmed that the cable of Configuration 1, which is an example, can transmit signals of 4 GHz or higher, particularly signals of 5 GHz or higher. Note that FIG. 7 shows that there is no significant insertion loss in the frequency band up to 10 GHz and signals can be transmitted, but it has also been confirmed that there is no significant insertion loss and signals can be transmitted in higher frequency bands, for example, frequency bands higher than 10 GHz.

[0153] On the other hand, for the cable of Configuration 2, which is a comparative example, it was confirmed that a large insertion loss was observed when the frequency exceeded 4 GHz, and it was not applicable for transmitting signals of 4 GHz or higher. [Experimental Example 2] For the in-vehicle cable 10 having the cross-sectional shape shown in FIG. 1, evaluations of abrasion resistance, flammability, and flexibility were performed. All of Experimental Examples 2-1 to 2-6 are examples.

[0154] The in-vehicle cable 10 was manufactured in the same manner as in the case of Configuration 1 of Experimental Example 1, except that the thickness of the outer sheath 16 was adjusted to the values shown in Table 2 in each experimental example.

[0155] Regarding the abrasion resistance, an evaluation of the abrasion resistance was performed by a tape test based on JASO D 618. At this time, the covered wire of each sample was cut out to a length of 1000 mm, and a #150G abrasive tape was pressed with a pressing load of 1.9 kg. Then, the tape was fed out at a tape moving speed of 1500 mm / min, and the amount of tape fed out until the conductor was exposed was measured.

[0156] Regarding the flammability, a horizontal combustion test was performed in accordance with JASO D 618. In this horizontal combustion test, the flame of a Bunsen burner was brought into contact with the lower side of the center of the horizontally held wire at an angle of 20 degrees for 30 seconds, and the time until the flame went out was measured.

[0157] Regarding flexibility, as shown in FIG. 8, an evaluation cable 80 with a length of 50 cm was placed on a table 81, and the cable 80 protruded 25 cm from the table 81. That is, the length L801 and the length L802 in the figure are each 25 cm.

[0158] At this time, it was evaluated by measuring the distance L80 between the ground 82 and the end 80A of the cable 80. The smaller L80 is, the more the in-vehicle cable is bent, which means that it has excellent flexibility.

[0159] Regarding abrasion resistance, when it was 250 cm or more, it was evaluated as A, when it was 200 cm or more and less than 250 cm, it was evaluated as B, and when it was less than 200 cm, it was evaluated as C. When the evaluation is A, it means that the abrasion resistance is the most excellent, that is, it is difficult to wear, and when the evaluations are B and C in order, it means that the abrasion resistance decreases.

[0160] Regarding flammability, when it was 30 seconds or less, it was evaluated as A, when it was longer than 30 seconds and 40 seconds or less, it was evaluated as B, and when it was longer than 40 seconds, it was evaluated as C. When the evaluation is A, it means that the flammability is the most excellent, that is, it is difficult to burn, and when the evaluations are B and C in order, it means that the flammability decreases.

[0161] Regarding flexibility, when it was 130 mm or less, it was evaluated as A, when it was longer than 130 mm and 135 mm or less, it was evaluated as B, and when it was longer than 135 mm, it was evaluated as C. When the evaluation is A, it means that the flexibility is the most excellent, that is, it can be easily bent, and when the evaluations are B and C in order, it means that the flexibility decreases.

[0162] As a comprehensive evaluation, for the above three types of evaluations, if any one includes C, it is evaluated as C; if it does not include C but includes B, it is evaluated as B; if all three types of evaluations are A, it is evaluated as A.

[0163] The thickness of the outer sheath of the in-vehicle cable used for evaluation and the evaluation results are shown in Table 2.

[0164]

Table 2

[0165] Experimental Example 3-1 is the evaluation result for the in-vehicle cable of Configuration 1 and becomes an example.

[0166] Experimental Example 3-2 is the evaluation result for the in-vehicle cable of Configuration 2 and becomes a comparative example.

[0167] Experimental Example 3-3 is the evaluation result for the in-vehicle cable of Configuration 3 and becomes a comparative example. (1) Regarding the cable of Configuration 3 The cable of Configuration 3 has the cross-sectional structure shown in Fig. 6 and has two conductors 61 that are single wires instead of stranded wires. The conductor diameter D61 of the conductor 61 is 0.41 mm as shown in Table 1, and the distance L61 between the conductors is 1.4 mm. As the conductor 61, a tin-plated copper wire was used.

[0168] And the two conductors 61 are collectively covered by an insulating layer 62. As the material of the insulating layer 62, polypropylene is used and cross-linking is not performed. The width W621 of the insulating layer 62 is 2.80 mm, and the height H62 of the insulating layer 62 is 1.40 mm.

[0169] In addition, a drain wire 612 is also arranged in the insulating layer 62.

[0170] An insulating tape layer 63 and a first shield layer 64 are provided on the outer periphery of the insulating layer 62. The insulating tape layer 63 and the first shield layer 64 are configured in the same manner as in the cable of Configuration 1 of Experimental Example 1.

[0171] Since the insulating tape layer 63 was formed using the insulating tape 130 shown in FIG. 3, the thickness of the insulating substrate layer 131, T131, is shown in Table 1 as the thickness of the insulating tape layer. Also, since the first shield layer 64 was formed using the metal tape 141 shown in FIG. 4A, the thickness T141 of the base material 1411 and the metal foil 1412 in the metal tape 141 is shown in Table 1.

[0172] The overall shield layer and the outer jacket were not provided.

[0173] Since the cables of Configuration 1 and Configuration 2 have the same configuration as in Experimental Example 1, the description is omitted here. (2) Evaluation For the evaluation of flexibility, as shown in FIG. 9, the cable 90 to be evaluated was placed and sandwiched between two mandrels 911 and 912 with a diameter of 4 mm arranged horizontally and parallel to each other, and a load of 200 g was applied vertically downward to the cable 90. In such a state, after bending the upper end of the cable 90 horizontally by 90° so as to contact the upper side of one mandrel 911, it was repeatedly bent horizontally by 90° so as to contact the upper side of the other mandrel 912.

[0174] The above repetition was performed while measuring the resistance value for all the conductors in the cable 90, and for any one of the conductors, the number of bending times until the resistance increased to 10 times or more of the initial resistance value was counted. Note that one bending cycle is defined as bending the cable to the left, then to the right, and then back to the left. The larger the number of bending times, which is the result of such a bending test, the better the flexibility.

[0175] Three cables with the same configuration were prepared and evaluated three times. The average value of the three times is also shown.

[0176] The evaluation results are shown in terms of the converted value obtained by converting the number of first bending times in Experimental Example 3-2 to 100. The larger this value, the better the flexibility. For example, the number of first bending times in Experiment 3-1 is more than 2.7 times that in the first bending of Experimental Example 3-2. The evaluation results are shown in Table 3.

[0177]

Table 3

[0178] On the other hand, it was confirmed that the cable of Experimental Example 3-3 is particularly inferior in flexibility because the conductor is not a stranded wire.

Explanation of Signs

[0179] 10, 20 Vehicle-mounted cables 101 Two-core cable 11, 11A, 11B Conductors (stranded wires) L11 Distance 111 Strand D111 Strand diameter 12 Insulation layer H12 Height W121 Width W122 Width 122 Flat part 13 Insulating tape layer 14 First shielding layer 15 Comprehensive shielding layer T15 Thickness 16 Outer sheath T16 Thickness 24 Second shielding layer 130 Insulating tape 13A, 13B Surfaces 131 Insulating base material layer T131 Thickness 132 Adhesive layer T132 Thickness 141 Metal tape 141A, 141B Surfaces 1411 Base material 1412 Metal foil (First metal foil) T141 Thickness 1413 Adhesive layer T1413 Thickness 142 Double-sided metal tape 142A, 142B Surfaces 1421 Substrate 1422 Upper metal foil (First metal foil, Second metal foil) 1423 Lower metal foil (First metal foil, Second metal foil) T142 Thickness 50 Cable 51 Conductor L51 Distance 511 Strand D511 Strand diameter 521 Insulation layer 52A, 52B Coated wire D52 Outer diameter of coated wire 53 Insulating tape layer 54 First shield layer 55 Comprehensive shield layer T55 Thickness 56 Outer sheath T56 Thickness 60 Cable 61 Conductor D61 Conductor diameter 612 Drain wire L61 Distance 62 Insulation layer W621 Width H12 Height 63 Insulating tape layer 64 First shield layer 71, 72 Wires 80 Cable L80 Length L801, L802 Length 80A End 81 Table 82 Ground 90 Cable 911, 912 Mandrel

Claims

1. An in-vehicle cable capable of transmitting signals of 4 GHz or higher, comprising: a plurality of twisted two-core cables; a second shield layer 24 including a second metal foil disposed on the outer periphery of the plurality of twisted two-core cables; an overall shield layer having a braided structure disposed so as to cover the outer periphery of the second shield layer; a jacket disposed on the outer periphery of the overall shield layer, wherein the two-core cable comprises: conductors which are two twisted wires arranged in parallel; an insulating layer covering the two conductors together; a first shield layer including a first metal foil disposed on the outer periphery of the insulating layer; The second shield layer includes a double-sided metal tape having the second metal foil on the upper and lower surfaces of a base material, which is spirally wound along the longitudinal direction of the plurality of two-core cables, and the second metal foil provided on the upper surface of the base material is in contact with the overall shield layer. An in-vehicle cable.

2. The in-vehicle cable according to claim 1, wherein the first shield layer is electrically connected to the overall shield layer via the second shield layer.

3. The in-vehicle cable according to claim 1 or claim 2, wherein the second metal foil is copper or aluminum.

4. The in-vehicle cable according to any one of claims 1 to 3, wherein the insulating layer includes one or more selected from polypropylene and cross-linked polyethylene.

5. The in-vehicle cable according to any one of claims 1 to 4, wherein the first metal foil is copper or aluminum.

6. The two-core cable has an insulating tape layer between the insulating layer and the first shield layer, The in-vehicle cable according to any one of claims 1 to 5, wherein the insulating tape layer includes an insulating tape provided with an insulating base material layer containing polyethylene terephthalate, which is spirally wound along the longitudinal direction of the insulating layer.

7. The in-vehicle cable according to any one of claims 1 to 6, wherein the thickness of the jacket is 0.3 mm or more and 1.0 mm or less.

8. The in-vehicle cable according to any one of claims 1 to 6, wherein the thickness of the jacket is 0.4 mm or more and 0.8 mm or less.

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