Large object wire

Abstract

To provide a thick wire excellent in flexibility.SOLUTION: A thick wire is for an electric vehicle, includes a conductor and an insulation layer covering an external surface of the conductor, and is to be used at a large current of 100 A or larger and a high voltage of 30 V or higher. The conductor includes a first twisted wire obtained by twisting a plurality of strands together, and a second twisted wire obtained by twisting a plurality of the first twisted wires together. A strand diameter of the strand is 0.18 to 0.35 mm. A secant modulus of the insulation layer is 15 to 41 MPa.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to thick wires.

Background Art

[0002] Patent Document 1 discloses an insulated wire including a conductor and an insulator covering the conductor, wherein the insulator is made of a halogen-free resin composition.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] For example, as disclosed in Patent Document 1, insulated wires have conventionally been used for wiring in automobiles and the like. By the way, in recent years, from the viewpoint of reducing the environmental load, the development and practical application of electric vehicles and the like have progressed, and from the viewpoint of shortening the charging time and the like, wires including conductors with a large cross-sectional area are also used so as to cope with large currents and high voltages.

[0005] However, a wire including a conductor with a large cross-sectional area is hard and difficult to bend. For this reason, there has been a problem that workability such as when attaching the wire to a vehicle of an electric vehicle deteriorates. Therefore, there has been a demand for a wire for an electric vehicle with a large cross-sectional area that is excellent in flexibility and can be easily bent when attached to a vehicle of an electric vehicle.

[0006] Therefore, an object of the present disclosure is to provide a thick wire excellent in flexibility.

Means for Solving the Problems

[0007] The thick wire of the present disclosure includes a conductor and an insulating layer covering the outer surface of the conductor, and is a thick wire for an electric vehicle used for a large current of 100 A or more and a high voltage of 30 V or more. The conductor includes a first stranded wire formed by stranding a plurality of strands, and a second stranded wire formed by stranding a plurality of the first stranded wires. The strand diameter of the strand is 0.18 mm or more and 0.35 mm or less. The secant modulus of the insulating layer is 15 MPa or more and 41 MPa or less.

Advantages of the Invention

[0008] According to the present disclosure, a thick wire excellent in flexibility can be provided.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4A

Figure 4B

Figure 5

Modes for Carrying Out the Invention

[0010] The modes 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 thick wire for an electric vehicle according to one aspect of the present disclosure includes a conductor and an insulating layer covering the outer surface of the conductor, and is a thick wire for an electric vehicle used for a large current of 100 A or more and a high voltage of 30 V or more, The conductor includes a first stranded wire formed by twisting a plurality of strands, and a second stranded wire formed by twisting a plurality of the first stranded wires, The strand diameter of the strand is 0.18 mm or more and 0.35 mm or less, The secant modulus of the insulating layer is 15 MPa or more and 41 MPa or less.

[0013] By having the conductor include a first stranded wire formed by twisting a plurality of strands and a second stranded wire formed by twisting a plurality of the first stranded wires, the flexibility of the conductor including the first stranded wire and the second stranded wire, and the thick wire including the conductor can be particularly enhanced. Also, even when the number of strands is large, the handling property of the strands can be enhanced by twisting the strands in multiple stages, and the productivity of the conductor can be enhanced.

[0014] By setting the strand diameter of the strand included in the conductor to 0.35 mm or less, the strand diameter of each strand constituting the conductor can be sufficiently suppressed, and the flexibility of the conductor formed by twisting the strands and the thick wire including the conductor can be enhanced.

[0015] By setting the strand diameter of the strand included in the conductor to 0.18 mm or more, the number of strands constituting the conductor can be suppressed, the productivity of the thick wire can be enhanced, and the cost can be suppressed.

[0016] By setting the secant modulus of the insulating layer to 41 MPa or less, the flexibility of the insulating layer and the thick wire including the insulating layer can be enhanced.

[0017] Also, by setting the secant modulus of the insulating layer to 15 MPa or more, it is possible to prevent the adhesion of the insulating layer to the conductor from becoming excessively high, improve the flexibility of the large-diameter wire, and improve the workability when attaching it to the vehicle body of an automobile or the like.

[0018] (2) The conductor has a nominal cross-sectional area of 70 SQ, when the large-diameter wire is bent at the bent portion and the radius of curvature of the bent portion is changed from 100 mm to 50 mm, the repulsive force is 55 N or less, the conductor adhesion, which is the adhesion between the conductor and the insulating layer, may be 50 N or less.

[0019] By setting the nominal cross-sectional area of the conductor to 70 SQ, a large-diameter wire including a conductor with a particularly large cross-sectional area can be obtained, and a large-diameter wire capable of handling large currents and high voltages can be obtained.

[0020] When the repulsive force is within the above range according to the nominal cross-sectional area of the conductor, it means that the large-diameter wire is excellent in flexibility when bent. Therefore, by satisfying both the conductor adhesion, the large-diameter wire is particularly excellent in flexibility and can improve the workability when attaching it to the vehicle body of an automobile or the like. Also, when the conductor adhesion is within the above range, the adhesion between the conductor and the insulating layer is appropriate, and by satisfying it together with the above-mentioned repulsive force, the large-diameter wire is excellent not only in flexibility but also in peelability workability, and can improve the workability when attaching it to the vehicle body of an automobile or the like.

[0021] (3) The conductor has a nominal cross-sectional area of 95 SQ, when the large-diameter wire is bent at the bent portion and the radius of curvature of the bent portion is changed from 100 mm to 50 mm, the repulsive force is 70 N or less, the conductor adhesion, which is the adhesion between the conductor and the insulating layer, may be 50 N or less.

[0022] By setting the nominal cross-sectional area of the conductor to 95 SQ, a large-diameter wire including a conductor with a particularly large cross-sectional area can be obtained, and a large-diameter wire capable of handling large currents and high voltages can be obtained.

[0023] Depending on the nominal cross-sectional area of the conductor, when the repulsive force is within the above range, it means that the thick wire has excellent flexibility when bent. Therefore, by satisfying both the conductor adhesion, the thick wire is particularly excellent in flexibility and can improve workability when attached to the vehicle body of an automobile. Also, when the conductor adhesion is within the above range, the adhesion between the conductor and the insulating layer is appropriate. By satisfying this together with the aforementioned repulsive force, the thick wire is excellent not only in flexibility but also in peelability, and can improve workability when attached to the vehicle body of an automobile.

[0024] (4) The conductor has a nominal cross-sectional area of 120 SQ, When the thick wire is bent at the bent portion and the radius of curvature of the bent portion is changed from 100 mm to 50 mm, the repulsive force is 140 N or less, The conductor adhesion, which is the adhesion between the conductor and the insulating layer, may be 50 N or less.

[0025] By setting the nominal cross-sectional area of the conductor to 120 SQ, a thick wire including a conductor with a particularly large cross-sectional area can be obtained, and a thick wire corresponding to a large current and a high voltage can be obtained.

[0026] Depending on the nominal cross-sectional area of the conductor, when the repulsive force is within the above range, it means that the thick wire has excellent flexibility when bent. Therefore, by satisfying both the conductor adhesion, the thick wire is particularly excellent in flexibility and can improve workability when attached to the vehicle body of an automobile. Also, when the conductor adhesion is within the above range, the adhesion between the conductor and the insulating layer is appropriate. By satisfying this together with the aforementioned repulsive force, the thick wire is excellent not only in flexibility but also in peelability, and can improve workability when attached to the vehicle body of an automobile.

[0027] (5) The conductor may include a third stranded wire formed by stranding a plurality of the second stranded wires.

[0028] By having the conductor have a third stranded wire formed by stranding a plurality of second stranded wires, an appropriate space is formed between the individual wires and between the stranded wires, and the flexibility of the conductor including the first stranded wire, the second stranded wire, and the third stranded wire, and the large-sized electric wire including the conductor can be particularly enhanced. Further, even when the number of individual wires is large, by stranding the individual wires in multiple stages, the handleability of the individual wires can be enhanced, and the productivity of the conductor can be enhanced.

[0029] (6) The insulating layer contains an insulating resin, The insulating resin may include an ethylene-ethyl acrylate copolymer.

[0030] By having the insulating resin of the insulating layer contain an ethylene-ethyl acrylate copolymer (EEA), the heat resistance and flame retardancy of the insulating layer and the large-sized electric wire including the insulating layer can be particularly enhanced.

[0031] (7) The ethylene-ethyl acrylate copolymer may contain more than 10% by mass and less than 35% by mass of ethyl acrylate.

[0032] By having the ethylene-ethyl acrylate copolymer (EEA) contain more than 10% by mass of ethyl acrylate (EA), the flexibility of the insulating layer and the large-sized electric wire including the insulating layer can be enhanced. By having the ethylene-ethyl acrylate copolymer (EEA) contain less than 35% by mass of ethyl acrylate (EA), it is possible to suppress the insulating layer from becoming overly flexible and the adhesion to the conductor from increasing. For this reason, by having the ethylene-ethyl acrylate copolymer (EEA) contain less than 35% by mass of ethyl acrylate (EA), the flexibility of the large-sized electric wire can be enhanced.

[0033] (8) The insulating resin contains a polyethylene resin, and when the total content of the ethylene-ethyl acrylate copolymer and the polyethylene resin is 100% by mass, the content of the ethylene-ethyl acrylate copolymer may be more than 20% by mass and less than 90% by mass.

[0034] By containing polyethylene resin in the insulating resin, the flexibility of the insulating layer and the large-sized electric wire including the insulating layer can be particularly enhanced.

[0035] And by making the proportion of the ethylene-ethyl acrylate copolymer more than 20% by mass, the heat resistance and flame retardancy of the insulating layer and the large-sized electric wire including the insulating layer can be enhanced. Also, by making the proportion of the ethylene-ethyl acrylate copolymer less than 90% by mass, the flexibility of the insulating layer can be made appropriate and the flexibility of the large-sized electric wire can be enhanced.

[0036] [Details of Embodiments of the Present Disclosure] A specific example of a large-sized electric wire 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, and is shown by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims. [Large-Sized Electric Wire] In FIGS. 1 to 3, a configuration example of a cross section perpendicular to the longitudinal direction of the large-sized electric wire of the present embodiment is shown. The direction perpendicular to the paper surface in FIGS. 1 to 3 is the longitudinal direction of the large-sized electric wire. Note that the large-sized electric wire 20 shown in FIG. 2 can have the same configuration as the large-sized electric wire 10 shown in FIG. 1 except for the different configuration of the conductor 23. Also, the large-sized electric wire 30 shown in FIG. 3 can be configured in the same manner as the large-sized electric wires shown in FIGS. 1 and 2 except for having a shield layer and an outer coating. For this reason, mainly the large-sized electric wire 10 shown in FIG. 1 will be used for the description, and FIGS. 2 and 3 will be used for the description as necessary.

[0037] As shown in FIG. 1, the large-sized electric wire 10 of the present embodiment can include a conductor 13 and an insulating layer 14 that covers the outer surface of the conductor 13. (1) Regarding each member contained in the large-sized electric wire Each member contained in the large-sized electric wire of the present embodiment will be described. (1-1) Conductor (1-1-1) Nominal cross-sectional area The nominal cross-sectional area S13 of the conductor 13 is, for example, 70 SQ (70 mm 2 ) or more and 120 SQ (mm 2)The following can be adopted. The thick wire of this embodiment is a wire including a conductor 13 with a nominal cross-sectional area within the above range.

[0038] By setting the nominal cross-sectional area S13 of the conductor 13 to be 70 SQ (70 mm 2 ) or more and 120 SQ (mm 2 ) or less, it is possible to obtain a thick wire including a conductor with a particularly large cross-sectional area, and it can be a thick wire for an electric vehicle that can handle large currents and high voltages. As described above, for the thick wire of this embodiment, for example, a conductor 13 with a nominal cross-sectional area within the above range can be selected and applied. For the thick wire of this embodiment, for example, a conductor with a nominal cross-sectional area within the above range, and any one of conductors with nominal cross-sectional areas of 70 SQ, 95 SQ, and 120 SQ can be selected and applied.

[0039] The nominal cross-sectional area S13 means, when the conductor 13 is composed of a plurality of strands, the sum of the cross-sectional areas of each strand, which can be calculated by the product of the strand cross-sectional area and the number of strands, and can also be referred to as the calculated cross-sectional area.

[0040] A conductor with a nominal cross-sectional area S13 of 70 SQ does not mean that the sum of the cross-sectional areas of each strand is exactly 70 mm 2 but includes the case where the sum of the strand cross-sectional areas of each strand is 66.6 mm 2 or more and 71.9 mm 2 or less. That is, a conductor with a nominal cross-sectional area S13 of 70 SQ refers to a conductor in which the sum of the strand cross-sectional areas (conductor cross-sectional area) is circulated as 70 SQ.

[0041] A conductor with a nominal cross-sectional area S13 of 95 SQ does not mean that the sum of the cross-sectional areas of each strand is exactly 95 mm 2 but includes the case where the sum of the strand cross-sectional areas of each strand is 88.0 mm 2 or more and 95.4 mm 2 or less. That is, a conductor with a nominal cross-sectional area S13 of 95 SQ refers to a conductor in which the sum of the strand cross-sectional areas (conductor cross-sectional area) is circulated as 95 SQ.

[0042] A conductor with a nominal cross-sectional area S13 of 120 SQ does not mean that the sum of the cross-sectional areas of each strand is exactly 120 mm 2 Rather, it includes cases where the sum of the strand cross-sectional areas of each strand is 113 mm 2 or more and 122 mm 2 or less. That is, a conductor with a nominal cross-sectional area S13 of 120 SQ refers to a conductor whose total strand cross-sectional area (conductor cross-sectional area) is distributed as 120 SQ. (1-1-2) Regarding the configuration of the conductor The material of the conductor 13 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.

[0043] The conductor 13 can be composed of a single wire or a stranded wire formed by twisting a plurality of strands. In particular, from the perspective of enhancing the flexibility of a large-diameter wire, for example, as shown in FIG. 1, the conductor 13 is preferably a stranded wire formed by twisting a plurality of strands 11. Hereinafter, a configuration example in the case where the conductor 13 is a stranded wire will be described. (Strand diameter) When the conductor 13 is a stranded wire formed by twisting a plurality of strands, the strand diameter D11 of the strand 11 is preferably 0.18 mm or more and 0.35 mm or less, and more preferably 0.20 mm or more and 0.32 mm or less.

[0044] By setting the strand diameter D11 of the strand 11 included in the conductor 13 to 0.35 mm or less, the strand diameter D11 of each strand 11 constituting the conductor 13 can be sufficiently suppressed, and the flexibility of the conductor 13 formed by twisting the strands 11 and the large-diameter wire 10 including the conductor 13 can be particularly enhanced.

[0045] However, if the strand diameter of the strand 11 included in the conductor 13 is made excessively thin, the number of strands 11 constituting the conductor 13 will become very large, resulting in a decrease in productivity and a factor in cost increase. Also, even if the strand diameter of the strand 11 is made excessively thin, the influence on the flexibility of the conductor 13 and the large-diameter wire 10 including the conductor 13 becomes small. Therefore, by setting the strand diameter D11 of the strand 11 included in the conductor 13 to 0.18 mm or more, the number of strands constituting the conductor 13 can be suppressed, the productivity of the large-diameter wire can be increased, and the cost can be suppressed. (Regarding the structure of the stranded wire) When the conductor 13 is a stranded wire formed by twisting a plurality of strands 11, from the viewpoint of productivity and the like, it is preferable to twist the plurality of strands in multiple stages.

[0046] That is, as shown in FIG. 1, the conductor 13 can include a first stranded wire 121 formed by twisting a plurality of strands 11, and a second stranded wire 122 formed by twisting a plurality of first stranded wires 121.

[0047] By having the conductor 13 include a first stranded wire 121 formed by twisting a plurality of strands 11 and a second stranded wire 122 formed by twisting a plurality of first stranded wires 121, the flexibility of the conductor 13 including the first stranded wire 121 and the second stranded wire 122, and the large-sized electric wire 10 including the conductor 13 can be particularly enhanced. Further, even when the number of strands 11 is large, by twisting the strands 11 in multiple stages, the handleability of the strands 11 can be enhanced, and the productivity of the conductor 13 can be enhanced.

[0048] In the case of the large-sized electric wire 10 shown in FIG. 1, each first stranded wire 121 is formed by twisting 69 strands 11, and the second stranded wire 122 is formed by twisting 19 first stranded wires 121. In the case of the large-sized electric wire 10 shown in FIG. 1, the second stranded wire 122 is the conductor 13.

[0049] However, the number of strands constituting the first stranded wire 121 and the number of first stranded wires 121 constituting the second stranded wire 122 are not limited to the above examples, and can be any number. For example, the number of strands 11 constituting the first stranded wire 121 is preferably 20 or more and 150 or less, and more preferably 23 or more and 120 or less. By setting the number of strands 11 constituting the first stranded wire 121 to 20 or more, the number of first stranded wires 121 included in the conductor 13 can be suppressed, and the productivity in manufacturing the conductor 13 can be enhanced. Further, by setting the number of strands 11 constituting the first stranded wire 121 to 150 or less, the productivity in manufacturing the first stranded wire 121 can be enhanced.

[0050] Further, for example, the number of the first twisted wires 121 constituting the second twisted wire 122 is preferably 5 or more and 50 or less, and more preferably 7 or more and 40 or less. By setting the number of the first twisted wires 121 constituting the second twisted wire 122 to 5 or more, sufficient number of the strands 11 included in the conductor 13 and the first twisted wires 121 can be ensured, and even when the strand diameter D11 is small, the cross-sectional area of the conductor 13 can be made sufficiently large. Further, by setting the number of the first twisted wires 121 constituting the second twisted wire 122 to 50 or less, the productivity in manufacturing the second twisted wire 122 can be increased.

[0051] In FIG. 1, an example in which the conductor 13 has the first twisted wire 121 and the second twisted wire 122 is shown, but the present invention is not limited to such a form. For example, like the thick wire 20 shown in FIG. 2, the conductor 23 may have a first twisted wire 121 formed by twisting a plurality of strands 11, a second twisted wire 122 formed by twisting a plurality of the first twisted wires 121, and a third twisted wire 123 formed by twisting a plurality of the second twisted wires 122. That is, the conductor 23 may have a third twisted wire 123 formed by twisting a plurality of the second twisted wires 122.

[0052] Since the conductor 23 has the third twisted wire 123 formed by twisting a plurality of the second twisted wires 122, an appropriate space is formed between the strands and between the twisted wires, and the flexibility of the conductor 23 including the first twisted wire 121, the second twisted wire 122, and the third twisted wire 123 and the thick wire 20 including the conductor 23 is particularly enhanced. Further, even when the number of the strands 11 is large, the handleability of the strands 11 can be improved by twisting the strands 11 in multiple stages, and the productivity of the conductor 23 can be increased.

[0053] In the case of the thick wire 20 shown in FIG. 2, each first twisted wire 121 is formed by twisting 22 strands 11, the second twisted wire 122 is formed by twisting 7 first twisted wires 121, and the third twisted wire 123 is formed by twisting 7 second twisted wires 122. In the thick wire 20 shown in FIG. 2, the third twisted wire 123 is the conductor 23.

[0054] However, the number of strands constituting the first twisted strand 121, the number of first twisted strands 121 constituting the second twisted strand 122, and the number of second twisted strands 122 constituting the third twisted strand 123 are not limited to the above examples and can be any number. For example, the number of second twisted strands 122 constituting the third twisted strand 123 is preferably 5 or more and 20 or less.

[0055] By setting the number of second twisted strands 122 constituting the third twisted strand 123 to 5 or more, the number of strands 11 included in the conductor 13, the number of first twisted strands 121, and the number of second twisted strands 122 can be ensured sufficiently, and even when the strand diameter D11 is thin, the cross-sectional area of the conductor 23 can be made sufficiently large. Further, by setting the number of second twisted strands 122 constituting the third twisted strand 123 to 20 or less, the productivity in manufacturing the third twisted strand 123 can be increased.

[0056] In FIG. 2, an example in which the conductor 23 has the first twisted strand 121, the second twisted strand 122, and the third twisted strand 123 is shown, but the present invention is not limited to such a form, and a fourth twisted strand formed by twisting a plurality of third twisted strands 123 or the like may be further twisted in multiple stages with strands and twisted strands.

[0057] As shown in FIGS. 1 and 2, when the conductor has a configuration in which a plurality of strands are twisted in multiple stages, the twisting direction is not particularly limited.

[0058] When the conductor 13 has a plurality of strands, the adhesion to the insulating layer 14 and further the flexibility of the thick wire 10 may change depending on the strand diameter, twisting direction, twisting pitch, and other twisting conditions of the plurality of strands. Therefore, it is preferable to perform a preliminary test or the like to select the twisting conditions of the plurality of strands constituting the conductor 13. (1-2) Insulating layer (1-2-1) Insulating resin As shown in FIG. 1, the insulating layer 14 can cover the outer surface of the conductor 13, specifically, the outer surface along the longitudinal direction of the thick wire 10. The insulating layer 14 can contain an insulating resin. The insulating resin is not particularly limited, but as the insulating resin, a material that has sufficient flexibility while suppressing the adhesion to the conductor 13 and enhancing the flexibility of the thick wire 10 can be preferably used. (Polyolefin resin) The insulating resin preferably contains, for example, a polyolefin resin. In particular, in order to impart appropriate flexibility to the insulating layer 14, it is more preferable that the insulating resin contains a copolymer of an olefin and a polar comonomer.

[0059] As the copolymer of an olefin and a polar comonomer, it is preferable to use one or more selected from, for example, ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl acrylate copolymer (EMA), ethylene-vinyl acetate copolymer (EVA), etc. As the copolymer of an olefin and a polar comonomer, ethylene-ethyl acrylate copolymer (EEA) can be more preferably used. That is, it is more preferable that the insulating resin contains ethylene-ethyl acrylate copolymer (EEA).

[0060] This is because when the insulating resin of the insulating layer 14 contains ethylene-ethyl acrylate copolymer (EEA), the heat resistance and flame retardancy of the insulating layer 14 and the large-sized electric wire including the insulating layer 14 can be particularly enhanced.

[0061] When the insulating resin of the insulating layer 14 contains ethylene-ethyl acrylate copolymer (EEA), the flexibility can be adjusted by selecting the content ratio of ethyl acrylate (EA) which is a comonomer.

[0062] Conventionally, it has been considered that the higher the flexibility of the insulating layer 14, the higher the flexibility of the large-sized electric wire 10 including the insulating layer 14 can be. However, according to the study by the inventor of the present invention, for example, when the nominal cross-sectional area of the conductor 13 is large, since the area of the outer surface of the conductor 13 is large, if the flexibility of the insulating layer 14 is excessively increased, the adhesion between the conductor 13 and the insulating layer 14 will increase. For this reason, the flexibility as the large-sized electric wire 10 may decrease.

[0063] Therefore, when the insulating resin of the insulating layer 14 contains ethylene-ethyl acrylate copolymer (EEA), it is preferable that the ethylene-ethyl acrylate copolymer (EEA) contains more than 10% by mass and less than 35% by mass of ethyl acrylate (EA), and more preferably contains 15% by mass or more and 30% by mass or less.

[0064] When the ethylene-ethyl acrylate copolymer (EEA) contains more than 10% by mass of ethyl acrylate (EA), the flexibility of the insulating layer 14 and the large-sized wire 10 including the insulating layer 14 can be enhanced. When the ethylene-ethyl acrylate copolymer (EEA) contains less than 35% by mass of ethyl acrylate (EA), it is possible to suppress the excessive softening of the insulating layer 14 and the increase in the adhesion to the conductor 13. For this reason, when the ethylene-ethyl acrylate copolymer (EEA) contains less than 35% by mass of ethyl acrylate (EA), the flexibility of the large-sized wire 10 can be enhanced. (Polyethylene resin) The insulating resin of the insulating layer 14 may also contain a polyethylene resin.

[0065] When the insulating resin contains a polyethylene resin, the flexibility of the insulating layer 14 and the large-sized wire 10 including the insulating layer 14 can be particularly enhanced.

[0066] As the polyethylene resin, it is preferable to use one or more selected from, for example, low-density polyethylene (LDPE), linear low-density polyethylene (L-LDPE), very-low-density polyethylene (VLDPE), etc., and it is more preferable to use very-low-density polyethylene (VLDPE).

[0067] Low-density polyethylene has a density of 0.91 g / cm 3 or more and less than 0.94 g / cm 3 of the material, and very-low-density polyethylene has a density of 0.87 g / cm 3 or more and less than 0.91 g / cm 3 of the material. The density of the material can be measured according to JIS K 6922 (2018).

[0068] By using the above-mentioned low-density polyethylene or ultra-low density polyethylene as the polyethylene resin, the flexibility of the insulating layer 14 and the large-diameter wire 10 including the insulating layer 14 can be particularly enhanced as compared with the case of using high-density polyethylene.

[0069] When the insulating layer 14 contains the above-mentioned polyolefin resin and the polyethylene resin, when the total content of the polyolefin resin and the polyethylene resin is 100% by mass, the proportion of the polyolefin resin content is preferably more than 20% by mass and less than 90% by mass, more preferably 25% by mass or more and 80% by mass or less, still more preferably 30% by mass or more and 70% by mass or less, and particularly preferably 30% by mass or more and 60% by mass or less.

[0070] As the polyolefin resin, the ethylene-ethyl acrylate copolymer can be preferably used as described above. Therefore, for example, when the total content of the ethylene-ethyl acrylate copolymer and the polyethylene resin is 100% by mass, the content of the ethylene-ethyl acrylate copolymer is preferably more than 20% by mass and less than 90% by mass, more preferably 25% by mass or more and 75% by mass or less, still more preferably 30% by mass or more and 70% by mass or less, and particularly preferably 30% by mass or more and 60% by mass or less.

[0071] By increasing the proportion of the polyolefin resin such as the ethylene-ethyl acrylate copolymer to more than 20% by mass, the heat resistance and flame retardancy of the insulating layer 14 and the large-diameter wire 10 including the insulating layer 14 can be enhanced. Further, by setting the proportion of the polyolefin resin to less than 90% by mass, the flexibility of the insulating layer 14 can be made appropriate and the flexibility of the large-diameter wire 10 can be enhanced.

[0072] The insulating resin may or may not be crosslinked. However, from the perspective of preventing deformation and a decrease in electrical insulation performance when an external force is applied in an environment with a relatively high temperature, that is, from the perspective of improving heat resistance to deformation, it is preferable that the insulating resin is crosslinked. The method of crosslinking is not particularly limited, and for example, crosslinking by irradiation with ionizing radiation such as γ-rays or electron beams, or chemical crosslinking such as peroxide crosslinking or silane crosslinking can be used. By performing crosslinking, the tensile strength and heat resistance can be improved.

[0073] The insulating layer 14 can be formed on the outer surface of the conductor 13 by, for example, extruding an insulating resin or an insulating layer raw material containing an additive. When crosslinking the insulating resin of the insulating layer 14, it can be carried out after the insulating layer is extruded. (1-2-2) Additive In addition to the above-mentioned insulating resin, the insulating layer 14 can also contain various additives. The insulating layer 14 can contain, as additives, for example, one or more selected from flame retardants, antioxidants, crosslinking agents, crosslinking aids, lubricants, and the like.

[0074] As the flame retardant, antioxidant, crosslinking agent, etc., known materials can be used and are not particularly limited.

[0075] Note that as the flame retardant, for example, a halogen-based flame retardant or a non-halogen-based flame retardant can be used. As the halogen-based flame retardant, a bromine-based flame retardant or 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. (1-2-3) Regarding the characteristics of the insulating layer The insulating layer 14 preferably has a secant modulus of 15 MPa or more and 41 MPa or less.

[0076] The secant modulus in this specification is a value obtained by measuring the load at 2% elongation when a test piece with a length of 100 mm is pulled in the longitudinal direction at a pulling speed of 50 mm / min using a tensile testing machine, dividing the load by the cross-sectional area, and multiplying the result by 50.

[0077] By setting the secant modulus of the insulating layer 14 to 41 MPa or less, the flexibility of the insulating layer 14 and the large-diameter wire 10 including the insulating layer 14 can be enhanced.

[0078] Also, by setting the secant modulus of the insulating layer 14 to 15 MPa or more, it is possible to prevent the adhesion of the insulating layer 14 to the conductor 13 from becoming excessively high, enhance the flexibility of the large-diameter wire, and enhance the workability when attaching it to the vehicle body of an automobile or the like. (1-3) Regarding other configurations The large-diameter wire of the present embodiment can also have a shield layer 35 and an outer peripheral coating 36 on the outer surface of the conductor 33 and the insulating layer 34, for example, like the large-diameter wire 30 shown in FIG. 3. Note that FIG. 3 is a cross-section perpendicular to the longitudinal direction of the large-diameter wire 30, and the description of the conductor 33 is shown in a simplified manner.

[0079] The configuration of the shield layer 35 is not particularly limited, and it can have, for example, the same configuration as the shield layer used in a coaxial cable or the like. The shield layer 35 can have, for example, a structure in which metal wires are wound horizontally around the outer periphery of the insulating layer 34 or arranged in a braided structure. As the material of the metal wire of the shield layer 35, copper, aluminum, copper alloy, or the like can be used. The metal wire of the shield layer may be subjected to a silver or tin plating treatment on the surface. Therefore, as the metal wire of the shield layer, for example, a silver-plated copper alloy, a tin-plated copper alloy, or the like can also be used.

[0080] By providing the shield layer 35, it is possible to reduce the intrusion of external noise and the leakage of signals to the outside.

[0081] The configuration of the outer peripheral coating 36 is not particularly limited, and it can have any configuration different from the above-described insulating layer, but it can also have the same configuration as the insulating layer, for example. Therefore, the description is omitted. (2) Regarding the characteristics of the large-diameter wire According to the study by the inventor of the present invention, when the nominal cross-sectional area of the conductor of a large-sized wire is large, in order to improve the flexibility of the large-sized wire, it is preferable that the following repulsive force and conductor adhesion force are within a predetermined range according to the nominal cross-sectional area of the conductor. Note that the flexibility of the large-sized wire means that the large-sized wire can be easily bent when attached to a vehicle of an automobile or the like.

[0082] Therefore, the repulsive force and the conductor adhesion force will be described below.

[0083] Note that the repulsive force and the conductor adhesion force vary depending on the configuration of the conductor and the material of the insulating layer. For this reason, it is preferable to conduct a preliminary test or the like, select the stranding conditions of a plurality of strands constituting the conductor, select the material of the insulating layer, etc., and adjust the repulsive force and the conductor adhesion force. (2-1) Repulsive force The large-sized wire 10 of the present embodiment preferably has a repulsive force according to the nominal cross-sectional area of the conductor 13.

[0084] The above-mentioned repulsive force can be evaluated in accordance with IEC60794-1-2 Method17c, and means the repulsive force when the large-sized wire is bent at the bending portion and the radius of curvature of the bending portion is changed from 100 mm to 50 mm. A smaller repulsive force means greater flexibility.

[0085] Specifically, for the evaluation of the repulsive force, first, as shown in FIG. 4A, the second end portion 402B in the longitudinal direction of the large-sized wire 40 is fixed by the fixing member 42 on the fixing surface 411A of the first fixing plate 411. Then, the large-sized wire 40 is bent so as to form a U shape at the bending portion 401 which is a point in the longitudinal direction of the large-sized wire 40, and the first end portion 402A in the longitudinal direction of the large-sized wire 40 is fixed to the fixing member 42 of the second fixing plate 412. Note that the fixing surface 411A of the first fixing plate 411 and the second fixing plate 412 are arranged to be parallel.

[0086] Then, from the state where the radius of curvature R1 at the bent portion 401 is 100 mm as shown in FIG. 4A to the state where the radius of curvature R2 at the bent portion 401 is 50 mm as shown in FIG. 4B, a load is applied and changed along the block arrow A. At this time, the applied load can be measured by a load cell (not shown) installed on the second fixing plate 412, and the repulsive force can be calculated.

[0087] The thick wire 10 preferably has a repulsive force corresponding to the nominal cross-sectional area of the conductor 13 as described above, and for example, preferably has a repulsive force below the values shown in Table 1 below.

[0088] That is, when the nominal cross-sectional area of the conductor 13 is 70 SQ, the repulsive force is preferably 55 N or less. When the nominal cross-sectional area of the conductor 13 is 95 SQ, the repulsive force is preferably 70 N or less. When the nominal cross-sectional area of the conductor 13 is 120 SQ, the repulsive force is preferably 140 N or less.

[0089] When the repulsive force is within the above range according to the nominal cross-sectional area of the conductor 13, it means that the thick wire 10 is excellent in flexibility when bent. Therefore, by satisfying together with the conductor adhesion force described later, the thick wire is particularly excellent in flexibility and can improve workability when attaching to the vehicle body of an automobile or the like.

[0090] The lower limit value of the repulsive force is not particularly limited, but it may be greater than 0 regardless of the nominal cross-sectional area of the conductor 13, and for example, it is preferably 5 N or more. (2-2) Conductor adhesion The thick wire 10 of the present embodiment preferably has a conductor adhesion force corresponding to the nominal cross-sectional area of the conductor 13.

[0091] The above-mentioned conductor adhesion force means the adhesion force between the conductor 13 and the insulating layer 14 when the conductor 13 is pulled out from the thick wire 10 along the longitudinal direction of the thick wire 10. The conductor adhesion force can be measured using, for example, a conductor adhesion force measuring jig 500 provided with a through hole through which only the conductor 53 shown in FIG. 5 passes.

[0092] Specifically, first, the insulation layer 54 of the large-diameter wire 50 is removed except for a part to expose the conductor 53. At this time, as shown in FIG. 5, the insulation layer 54 is left so that the length L of the insulation layer 54 along the longitudinal direction of the large-diameter wire 50 is 50 mm.

[0093] Then, the exposed conductor 53 is inserted into the through-hole of the conductor adhesion measuring jig 500. As a result, as shown in FIG. 5, the large-diameter wire 10 is set on the conductor adhesion measuring jig 500.

[0094] Next, with the conductor adhesion measuring jig 500 fixed, the large-diameter wire 10 is pulled at a speed of 250 mm / min along the longitudinal direction of the large-diameter wire 10 indicated by the block arrow B in FIG. 5. Then, when the conductor 53 peels off from the insulation layer 54 and the conductor 53 passes through the through-hole of the conductor adhesion measuring jig 500 and moves below the conductor adhesion measuring jig 500, the magnitude of the force applied is measured. The magnitude of the measured force can be taken as the conductor adhesion of the large-diameter wire.

[0095] The large-diameter wire preferably has a conductor adhesion corresponding to the nominal cross-sectional area of the conductor as described above. For example, it preferably has a conductor adhesion below the values shown in Table 1 below.

[0096] That is, when the nominal cross-sectional area of the conductor 13 is 70 SQ, the conductor adhesion is preferably 50 N or less. When the nominal cross-sectional area of the conductor 13 is 95 SQ, the conductor adhesion is preferably 50 N or less. When the nominal cross-sectional area of the conductor 13 is 120 SQ, the conductor adhesion is preferably 50 N or less.

[0097] When the conductor adhesion is within the above range according to the nominal cross-sectional area of the conductor 13, the adhesion between the conductor 13 and the insulation layer 14 is appropriate. By satisfying together with the above-described repulsive force, the large-diameter wire is excellent in flexibility and also in peelability in addition to flexibility, and can improve workability when attached to the vehicle body of an automobile or the like. The peelability means the ease of peeling of the insulation layer when peeling the insulation layer from the conductor at the end or the like of the large-diameter wire.

[0098] The lower limit value of the conductor adhesion is not particularly limited, but regardless of the nominal cross-sectional area of the conductor 13, it is preferably, for example, 5 N or more, and more preferably 10 N or more. By setting the conductor adhesion to 5 N or more, it is possible to prevent the conductor 13 and the insulating layer 14 from being displaced when handling the thick wire 10.

[0099]

Table 1

[0100] The above-mentioned large current means a current with a use current of 100 A or more. The above-mentioned high voltage is 30 V or more, and particularly preferably 30 V or more and 100 V or less in the case of alternating current, and 60 V or more and 1500 V or less in the case of direct current. In this specification, large current and high voltage have the same meaning.

[0101] Conventionally, in thick wires used for large current and high voltage, considering the allowable current, smoke generation characteristics, etc., the cross-sectional area of the conductor becomes large, so the flexibility is inferior, and there are problems in workability when attaching to vehicles of automobiles, etc. On the other hand, according to the thick wire of this embodiment, since it has sufficient flexibility, the workability when attaching to vehicles of automobiles, etc. can be improved.

Examples

[0102] Specific examples will be given below for explanation, but the present invention is not limited to these examples. (Evaluation method) First, the evaluation method of the thick wire produced in the following experimental examples will be described. (1) Strand diameter, outer diameter of conductor, outer diameter of thick wire, insulation layer thickness, calculated cross-sectional area The strand diameter D11 of the strand 11, the outer conductor diameter D13 which is the outer diameter of the conductor 13, the wire outer diameter D10 which is the outer diameter of the thick wire 10, and the insulation layer thickness were measured and calculated in accordance with JASO D618:2013.

[0103] Specifically, the wire outer diameter D10 was measured at three locations having substantially equal angles in the same plane perpendicular to the wire axis, and the average value was taken. This was done at three cross-sections, i.e., at three locations, where the adjacent evaluation surfaces were 1 m apart along the longitudinal direction of the thick wire, and the maximum value, average value, and minimum value were recorded from the measurement results at the three locations. The wire outer diameter D10 was taken as this average value.

[0104] For the outer conductor diameter D13, after the thick wire was cut perpendicularly at the location where the wire outer diameter D10 was measured, the inner diameter of the insulation layer was measured in the same manner, and the maximum value was taken.

[0105] The insulation layer thickness T14 was obtained by calculating half of the difference between the obtained minimum wire outer diameter and the outer conductor diameter.

[0106] The strand diameter D11 of the strand 11 was also measured and calculated in the same manner as in the case of the wire outer diameter described above.

[0107] In Tables 2 to 6, the strand diameter D11 of the strand 11 is shown in the "strand diameter" column, the outer conductor diameter D13 of the conductor 13 is shown in the "conductor diameter" column, and the wire outer diameter D10 which is the outer diameter of the thick wire 10 is shown in the "outer diameter" column, respectively. The insulation layer thickness T14 is shown in the "insulation layer thickness" column in Tables 2 to 6.

[0108] From the diameter of each strand 11 which is the strand diameter D11, the cross-sectional area of each strand 11 (strand cross-sectional area) was calculated. Then, the cross-sectional area of the conductor 13 was calculated by multiplying the strand cross-sectional area by the number of strands contained in the conductor 13. The calculated cross-sectional area is shown in the "calculated cross-sectional area" column in Tables 2 to 6.

[0109] (2) Secant modulus When measuring the secant modulus, test pieces made under the same conditions as in each experimental example were prepared for the insulating layer. Then, a test piece with a length of 100 mm was pulled in the longitudinal direction at a pulling speed of 50 mm / min using a tensile testing machine, and the value obtained by dividing the load at 2% elongation by the cross-sectional area was measured. The secant modulus was calculated by multiplying this value by 50. (3) Resilience As shown in Fig. 4A, the second end portion 402B in the longitudinal direction of the thick wire 40 to be evaluated was fixed by the fixing member 42 on the fixing surface 411A of the first fixing plate 411. Then, the thick wire 40 was bent into a U shape at the bending portion 401, which is a point in the longitudinal direction of the thick wire 40, and the first end portion 402A in the longitudinal direction of the thick wire 40 was fixed to the fixing member 42 of the second fixing plate 412. Note that the fixing surface 411A of the first fixing plate 411 and the second fixing plate 412 were arranged to be parallel.

[0110] Then, from the state where the radius of curvature R1 at the bending portion 401 shown in Fig. 4A was 100 mm to the state where the radius of curvature R2 at the bending portion 401 shown in Fig. 4B was 50 mm, a load was applied and changed along the block arrow A. At this time, the applied load was measured by a load cell (not shown) installed on the second fixing plate 412, and the resilience was calculated.

[0111] The resilience was evaluated as A to C based on a standard corresponding to the nominal cross-sectional area of the conductor included in the thick wire according to the measured value. A means that the resilience is sufficiently small and the flexibility of the thick wire is excellent, and B and C mean that the flexibility decreases in this order. (4) Conductor adhesion The measurement was performed using a conductor adhesion measuring jig 500 provided with a through hole through which only the conductor 53 shown in Fig. 5 passes.

[0112] Specifically, first, a part of the insulating layer 54 of the thick wire 50 to be evaluated was removed to expose the conductor 53. At this time, as shown in Fig. 5, the insulating layer 54 was left so that the length L of the insulating layer 54 along the longitudinal direction of the thick wire 50 was 50 mm.

[0113] Then, the exposed conductor 53 was inserted into the through-hole of the conductor adhesion measuring jig 500. As a result, as shown in FIG. 5, the thick wire 10 was set on the conductor adhesion measuring jig 500.

[0114] Next, with the conductor adhesion measuring jig 500 fixed, the thick wire 10 was pulled at a speed of 250 mm / min along the longitudinal direction of the thick wire 10 indicated by the block arrow B in FIG. 5. Then, when the conductor 53 was peeled off from the insulating layer 54 and the conductor 53 passed through the through-hole of the conductor adhesion measuring jig 500 and moved below the conductor adhesion measuring jig 500, the magnitude of the force applied was measured. The magnitude of the measured force was defined as the conductor adhesion, which is the adhesion between the conductor and the insulating layer of the thick wire.

[0115] Based on the measured value, the conductor adhesion was evaluated as A to C according to the standard corresponding to the nominal cross-sectional area of the conductor of the thick wire. A means that the conductor adhesion is sufficiently small and the adhesion between the conductor and the insulating layer can be appropriately suppressed. B and C mean that the conductor adhesion increases in this order.

[0116] The thick wires in each experimental example will be described below. [Experimental Example 1] In the following Experimental Example 1, thick wires of Experimental Examples 1-1 to 1-11 with a nominal cross-sectional area of the conductor of 70 SQ were produced. Experimental Examples 1-3 to 1-9 are examples, and Experimental Examples 1-1, 1-2, 1-10, and 1-11 are comparative examples. [Experimental Example 1-1] In Experimental Example 1-1, as shown in FIG. 1, a thick wire including a conductor 13 and an insulating layer 14 covering the outer surface of the conductor 13 was produced in a cross-section perpendicular to the longitudinal direction. (Conductor) As shown in Table 2, the conductor 13 was formed by stranding 182 strands 11 with a strand diameter D11 of 0.16 mm to form a first stranded wire 121, and then stranding 19 of the first stranded wires 121 to form a second stranded wire 122. The second stranded wire 122 becomes the conductor 13.

[0117] The notation "19 / 182 / 0.16" in the column of the conductor configuration in Table 2 indicates that the right end shows the single wire diameter, and the second numerical value from the right end means the number of single wires that make up the first stranded wire formed by twisting the single wires of the single wire diameter. Also, the numerical value at the left end means the number of the first stranded wires that make up the second stranded wire formed by twisting the first stranded wires. (Insulation layer) After extruding the material of the insulation layer onto the outer surface of the conductor 13, a crosslinking treatment was performed by electron beam irradiation to form an insulation layer 14 that covers the outer surface of the conductor 13.

[0118] The insulation layer 14 is composed of a mixture of an insulating resin that is a copolymer of ethylene-ethyl acrylate (EEA) and very low density polyethylene (VLDPE).

[0119] As the ethylene-ethyl acrylate copolymer (EEA), a material with an ethyl acrylate (EA) content ratio of 25% by mass was used.

[0120] Also, in the insulating resin, the content ratio of the ethylene-ethyl acrylate copolymer (EEA) was set to 50% by mass, and the balance was very low density polyethylene (VLDPE).

[0121] As additives to the insulation layer 14, when the insulating resin was 100 parts by mass, a flame retardant was added at a ratio of 55 parts by mass, an antioxidant was added at 25 parts by mass, a lubricant was added at 1.5 parts by mass, and a crosslinking aid was added at 3 parts by mass. The secant modulus of the insulation layer 14 was 20 MPa.

[0122] In this experimental example, the large-diameter wire had a very large number of single wires, 3458, resulting in very high production costs and limited production equipment. Therefore, the evaluation of the repulsive force and the conductor adhesion was not performed. [Experimental Example 1-2] Regarding the conductor 13, as shown in Table 2, 93 single wires 11 with a single wire diameter D11 of 0.16 mm were twisted together to form a first stranded wire 121, and 37 of these first stranded wires 121 were twisted together to form a second stranded wire 122. The second stranded wire 122 becomes the conductor 13.

[0123] Except for the above points, a thick wire was produced in the same manner as in Experimental Example 1-1.

[0124] The thick wire of this experimental example had a very large number of 3,441 strands, resulting in extremely high production costs and limited production facilities. Therefore, the repulsive force and the evaluation of the conductor adhesion force were not performed. [Experimental Examples 1-3 to 1-11] Regarding the conductor 13, except for changing the conductor configuration as shown in Table 2, a thick wire was produced in the same manner as in Experimental Example 1-1. That is, a thick wire was produced in the same manner as in Experimental Example 1-1 except for changing the strand diameter, the number of strands constituting the first twist, and the number of first twists constituting the second twist.

[0125] The obtained thick wire was evaluated as described above. The evaluation results are shown in Table 2.

[0126] Regarding the repulsive force, it was evaluated as A when it was 45 N or less, B when it exceeded 45 N and was 55 N or less, and C when it exceeded 55 N.

[0127] Regarding the conductor adhesion force, it was evaluated as A when it was 30 N or less, B when it exceeded 30 N and was 50 N or less, and C when it exceeded 50 N.

[0128] Regarding the cost, evaluations from A to C were made according to the manufacturing cost, that is, the total of the material cost and the processing cost. Note that the material cost increases as the amount of copper contained, for example, increases, and the processing cost increases as the total number of strands or the number of second twists increases, for example. A has the lowest cost, and the cost increases in the order of B and C. It means that the cost can be sufficiently suppressed in the case of A or B. The cost evaluations for the following Experimental Examples 2 and 3 were also performed in the same manner. When the cost evaluation was C, the evaluations of the repulsive force and the conductor adhesion force were not performed, and the following comprehensive determination was set as C.

[0129] Regarding the comprehensive judgment, for the evaluation of the repulsive force, conductor adhesion, and cost, with A being 3 points, B being 2 points, and C being -1 point, when the total score was 9 points, it was evaluated as A; when it was 6 points or more and 8 points or less, it was evaluated as B; and when it was 5 points or less, it was evaluated as C.

[0130] When the comprehensive judgment is A or B, it means that the thick wire has appropriate adhesion between the conductor 13 and the insulating layer 14, and is excellent in flexibility and cost.

[0131]

Table 2

[0132] For the thick wires of Experimental Example 1-3 to Experimental Example 1-9, the comprehensive judgment was A or B, and it was confirmed that thick wires excellent in flexibility and cost were obtained. On the other hand, the comprehensive judgment of the thick wires of Experimental Example 1-10 and Experimental Example 1-11 was C. For Experimental Example 1-10 and Experimental Example 1-11, it was confirmed that they were inferior in flexibility.

[0133] From the above results, it was confirmed that by changing the configuration of the conductor, specifically, for example, by changing the strand diameter of the strands, the flexibility of the thick wire changed.

[0134] Also, for a thick wire with a nominal cross-sectional area of the conductor of 70 SQ, when the repulsive force was 55 N or less and the conductor adhesion was 50 N or less, it was confirmed that the evaluations of the repulsive force, conductor adhesion, cost, and the comprehensive judgment were all A or B. [Experimental Example 2] In the following Experimental Example 2, thick wires of Experimental Example 2-1 to Experimental Example 2-11 with a nominal cross-sectional area of the conductor of 95 SQ were manufactured. Experimental Example 2-3 to Experimental Example 2-9 were examples, and Experimental Example 2-1, Experimental Example 2-2, Experimental Example 2-10, and Experimental Example 2-11 were comparative examples. [Experimental Example 2-1] In Experimental Example 2-1, an insulated electric wire including a conductor 13 and an insulating layer 14 covering the outer surface of the conductor 13 was fabricated as shown in FIG. 1 in a cross section perpendicular to the longitudinal direction. (Conductor) As shown in Table 3, the conductor 13 was formed by stranding 240 strands 11 with a strand diameter D11 of 0.16 mm to form a first stranded wire 121, and then stranding 19 of the first stranded wires 121 to form a second stranded wire 122. The second stranded wire 122 became the conductor 13.

[0135] A thick wire was fabricated in the same manner as in Experimental Example 1-1 except for the above points.

[0136] However, since the thick wire in this experimental example had a very large number of 4,560 strands, the production cost was extremely high, and the equipment capable of production was limited, the repulsive force and the conductor adhesion force were not evaluated. [Experimental Example 2-2] Regarding the conductor 13, as shown in Table 3, 126 strands 11 with a strand diameter D11 of 0.16 mm were stranded to form a first stranded wire 121, and then 37 of the first stranded wires 121 were stranded to form a second stranded wire 122. The second stranded wire 122 became the conductor 13.

[0137] A thick wire was fabricated in the same manner as in Experimental Example 2-1 except for the above points.

[0138] However, since the thick wire in this experimental example had a very large number of 4,662 strands, the production cost was extremely high, and the equipment capable of production was limited, the repulsive force and the conductor adhesion force were not evaluated. [Experimental Examples 2-3 to 2-11] Regarding the conductor 13, a thick wire was fabricated in the same manner as in Experimental Example 2-1 except for the points where the configuration was changed as shown in Table 3. That is, a thick wire was fabricated in the same manner as in Experimental Example 2-1 except for changing the strand diameter, the number of strands constituting the first stranded wire, and the number of the first stranded wires constituting the second stranded wire.

[0139] In Experimental Example 2-3, 22 strands of wire 11 with a wire diameter D11 of 0.20 mm were twisted together to form a first twisted wire 121, 7 of the first twisted wires 121 were twisted together to form a second twisted wire 122, and 19 of the second twisted wires 122 were twisted together to form a third twisted wire 123. Similar to the case of the thick wire 20 shown in FIG. 2, the third twisted wire 123 becomes the conductor 23.

[0140] The above-described evaluation was performed on the obtained thick wire. The evaluation results are shown in Table 3.

[0141] Regarding the repulsive force, it was evaluated as A when it was 60 N or less, B when it exceeded 60 N and was 70 N or less, and C when it exceeded 70 N.

[0142] Regarding the conductor adhesion force, it was evaluated as A when it was 30 N or less, B when it exceeded 30 N and was 50 N or less, and C when it exceeded 50 N.

[0143] Regarding the cost, evaluations of A to C were performed according to the manufacturing cost. A has the lowest cost, and the costs increase in the order of B and C. It means that the cost can be sufficiently suppressed in the case of A or B. When the cost evaluation was C, the evaluations of the repulsive force and the conductor adhesion force were not performed, and the following comprehensive determination was set as C.

[0144] Regarding the comprehensive determination, for the evaluations of the above repulsive force, conductor adhesion force, and cost, with A being 3 points, B being 2 points, and C being -1 point, when the total score was 9 points, it was evaluated as A, when it was 6 points or more and 8 points or less, it was evaluated as B, and when it was 5 points or less, it was evaluated as C.

[0145] When the comprehensive determination is A or B, it means that the thick wire has appropriate adhesion between the conductor 13 and the insulating layer 14, and is excellent in flexibility and cost.

[0146]

Table 3

[0147] For the thick wires in Experimental Example 2-3 to Experimental Example 2-9, the comprehensive judgment was A or B, and it was confirmed that thick wires with excellent flexibility and cost were obtained. On the other hand, the comprehensive judgment of the thick wires in Experimental Example 2-10 and Experimental Example 2-11 was C. For Experimental Example 2-10 and Experimental Example 2-11, it was confirmed that they were inferior in flexibility.

[0148] That is, it was confirmed that by changing the configuration of the conductor, specifically, for example, by changing the strand diameter of the strands, the flexibility of the thick wire changed.

[0149] Also, for the thick wire with a nominal cross-sectional area of the conductor of 95 SQ, when the repulsive force was 70 N or less and the conductor adhesion was 50 N or less, it was confirmed that the evaluations of the repulsive force, the conductor adhesion, the cost, and the comprehensive judgment all became A or B. [Experimental Example 3] In the following Experimental Example 3, thick wires of Experimental Example 3-1 to Experimental Example 3-9 with a nominal cross-sectional area of the conductor of 120 SQ were produced. Experimental Example 3-3 to Experimental Example 3-7 are examples, and Experimental Example 3-1, Experimental Example 3-2, Experimental Example 3-8, and Experimental Example 3-9 are comparative examples. [Experimental Example 3-1] In Experimental Example 3-1, as shown in FIG. 1, in a cross-section perpendicular to the longitudinal direction, an insulated wire including a conductor 13 and an insulating layer 14 covering the outer surface of the conductor 13 was produced. (Conductor) As shown in Table 4, the conductor 13 was formed by twisting 310 strands 11 with a strand diameter D11 of 0.16 mm to form a first twisted strand 121, and then twisting 19 of the first twisted strands 121 to form a second twisted strand 122. The second twisted strand 122 became the conductor 13.

[0150] Except for the above points, the thick wire was produced in the same manner as in Experimental Example 1-1.

[0151] However, since the thick wire in this experimental example had a very large number of strands, 5,890, resulting in extremely high production costs and limited production equipment, the repulsive force and the evaluation of conductor adhesion were not performed. [Experimental Example 3-2] Regarding the conductor 13, as shown in Table 4, 160 strands of strands 11 with a strand diameter D11 of 0.16 mm were twisted together to form a first twisted wire 121, and 37 of the first twisted wires 121 were twisted together to form a second twisted wire 122. The second twisted wire 122 became the conductor 13.

[0152] A thick wire was produced in the same manner as in Experimental Example 3-1, except for the above points.

[0153] However, since the thick wire in this experimental example had a very large number of strands, 5,920, resulting in extremely high production costs and limited production equipment, the repulsive force and the evaluation of conductor adhesion were not performed. [Experimental Examples 3-3 to 3-9] Regarding the conductor 13, a thick wire was produced in the same manner as in Experimental Example 3-1, except for the points where the configuration was changed as shown in Table 3.

[0154] The above-mentioned evaluation was performed on the obtained thick wire. The evaluation results are shown in Table 4.

[0155] Regarding the repulsive force, it was evaluated as A when it was 130 N or less, B when it exceeded 130 N and was 140 N or less, and C when it exceeded 140 N.

[0156] Regarding the conductor adhesion, it was evaluated as A when it was 30 N or less, B when it exceeded 30 N and was 50 N or less, and C when it exceeded 50 N.

[0157] Regarding the cost, evaluations of A to C were performed according to the manufacturing cost. A had the lowest cost, and the costs increased in the order of B and C. It means that the cost was sufficiently suppressed in the case of A or B. When the cost evaluation was C, the evaluation of the repulsive force and the conductor adhesion was not performed, and the following comprehensive determination was set as C.

[0158] Regarding the comprehensive judgment, for the evaluation of the repulsive force, conductor adhesion, and cost, assuming A is 3 points, B is 2 points, and C is -1 point, when the total score is 9 points, it is evaluated as A; when it is 6 points or more and 8 points or less, it is evaluated as B; when it is 5 points or less, it is evaluated as C.

[0159] When the comprehensive judgment is A or B, it means that the adhesion between the conductor 13 and the insulating layer 14 of the thick wire is appropriate, and it is excellent in flexibility and cost.

[0160]

Table 4

[0161] For the thick wires of Experimental Examples 3-3 to 3-7, the comprehensive judgment was A or B, and it was confirmed that thick wires excellent in flexibility and cost were obtained. On the other hand, the comprehensive judgment results of the thick wires of Experimental Examples 3-8 and 3-9 were C. For Experimental Examples 3-9 and 3-10, it was confirmed that they were inferior in flexibility.

[0162] That is, it was confirmed that by changing the configuration of the conductor, specifically, for example, by changing the strand diameter of the strands, the flexibility of the thick wire changed.

[0163] Also, for the thick wire with a nominal cross-sectional area of the conductor of 120 SQ, when the repulsive force is 140 N or less and the conductor adhesion is 50 N or less, it was confirmed that the evaluations of the repulsive force, conductor adhesion, cost, and comprehensive judgment were all A or B. [Experimental Example 4] In the following Experimental Example 4, thick wires of Experimental Examples 4-1 to 4-5 with a nominal cross-sectional area of the conductor of 95 SQ were produced. Experimental Examples 4-2 to 4-4 are examples, and Experimental Examples 4-1 and 4-5 are comparative examples. [Experimental Example 4-1] In Experimental Example 4-1, an insulated wire including a conductor 13 and an insulating layer 14 covering the outer surface of the conductor 13 was produced as shown in FIG. 1 in a cross section perpendicular to the longitudinal direction. (Conductor) As shown in Table 5, the conductor 13 was formed by stranding 91 strands 11 with a strand diameter D11 of 0.26 mm to form a first stranded wire 121, and then stranding 19 of the first stranded wires 121 to form a second stranded wire 122. The second stranded wire 122 became the conductor 13. (Insulating layer) After extruding the material of the insulating layer onto the outer surface of the conductor 13, a crosslinking treatment was performed by electron beam irradiation to form an insulating layer 14 covering the outer surface of the conductor 13.

[0164] The insulating layer 14 is composed of a mixture of an insulating resin that is a copolymer of ethylene and ethyl acrylate (EEA) and very low density polyethylene (VLDPE).

[0165] As the copolymer of ethylene and ethyl acrylate (EEA), a material with an ethyl acrylate (EA) content of 10% by mass was used.

[0166] Also, in the insulating resin, the content ratio of the copolymer of ethylene and ethyl acrylate (EEA) was 50% by mass, and the balance was very low density polyethylene (VLDPE).

[0167] As additives to the insulating layer 14, when the insulating resin was 100 parts by mass, a flame retardant was added in a proportion of 55 parts by mass, an antioxidant was added in a proportion of 25 parts by mass, a lubricant was added in a proportion of 1.5 parts by mass, and a crosslinking aid was added in a proportion of 3 parts by mass.

[0168] As shown in Table 5, the outer diameter D10 of the obtained large-diameter wire 10 was 16.9 mm.

[0169] The above-described evaluation was performed on the obtained large-diameter wire. The evaluation results are shown in Table 5.

[0170] Regarding the repulsive force, it was evaluated as A when it was 60 N or less, evaluated as B when it exceeded 60 N and was 70 N or less, and evaluated as C when it exceeded 70 N.

[0171] Regarding the conductor adhesion, when it was 30 N or less, it was evaluated as A; when it exceeded 30 N and was 50 N or less, it was evaluated as B; and when it exceeded 50 N, it was evaluated as C.

[0172] Regarding the comprehensive judgment, regarding the evaluation of the above-mentioned repulsive force and conductor adhesion, with A being 3 points, B being 2 points, and C being -1 point, when the total score was 6 points, it was evaluated as A; when it was 3 points or more and 5 points or less, it was evaluated as B; and when it was 2 points or less, it was evaluated as C.

[0173] When the comprehensive judgment is A or B, it means that the adhesion between the conductor 13 and the insulating layer 14 is appropriate, and the thick wire is excellent in flexibility. [Experimental Examples 4-2 to 4-5] As the ethylene-ethyl acrylate copolymer (EEA), a material with the content ratio of ethyl acrylate (EA) shown in the column of "Content ratio of EA in EEA" in Table 5 was used.

[0174] Except for the above points, thick wires were produced in the same manner as in Experimental Example 4-1, and the obtained thick wires were evaluated as described above. The evaluation results are shown in Table 5.

[0175]

Table 5

[0176] That is, it was confirmed that by changing the composition of the insulating layer, specifically, for example, by changing the secant modulus of the insulating layer, the flexibility of the thick wire changed.

[0177] Also, when the ethylene-ethyl acrylate copolymer contains more than 10% by mass and less than 35% by mass of ethyl acrylate, it was confirmed that the secant modulus of the insulating layer was 15 MPa or more and 41 MPa or less. And in this case, it was confirmed that the resilience, the evaluation of the conductor adhesion, and the comprehensive determination all became A or B. [Experimental Example 5] In the following Experimental Example 5, thick wires of Experimental Examples 5-1 to 5-7 with a nominal cross-sectional area of the conductor of 95 SQ were produced. Experimental Examples 5-2 to 5-6 are examples, and Experimental Examples 5-1 and 5-7 are comparative examples. [Experimental Example 5-1] In Experimental Example 5-1, as shown in FIG. 1, an insulated wire including a conductor 13 and an insulating layer 14 covering the outer surface of the conductor 13 was produced in a cross-section perpendicular to the longitudinal direction. (Conductor) As shown in Table 6, the conductor 13 was formed by stranding 91 strands 11 with a strand diameter D11 of 0.26 mm into a first stranded wire 121, and then stranding 19 of the first stranded wires 121 into a second stranded wire 122. The second stranded wire 122 becomes the conductor 13. (Insulating layer) After extruding the material of the insulating layer onto the outer surface of the conductor 13, a crosslinking treatment was performed by electron beam irradiation to form an insulating layer 14 covering the outer surface of the conductor 13.

[0178] The insulating layer 14 is composed of a mixture of an insulating resin of an ethylene-ethyl acrylate copolymer (EEA) and a very low density polyethylene (VLDPE).

[0179] As the ethylene-ethyl acrylate copolymer (EEA), a material with an ethyl acrylate (EA) content ratio of 25% by mass was used.

[0180] Also, in the insulating resin, the content ratio of the ethylene-ethyl acrylate copolymer (EEA) was 20% by mass, and the balance was very low density polyethylene (VLDPE).

[0181] In addition, as additives to the insulating layer 14, when the insulating resin is 100 parts by mass, a flame retardant was added in a proportion of 55 parts by mass, an antioxidant was added in a proportion of 25 parts by mass, a lubricant was added in a proportion of 1.5 parts by mass, and a crosslinking aid was added in a proportion of 3 parts by mass.

[0182] As shown in Table 6, the outer diameter D10 of the obtained large-sized wire 10 was 16.9 mm.

[0183] The above-described evaluation was performed on the obtained large-sized wire. The evaluation results are shown in Table 6.

[0184] Regarding the repulsive force, it was evaluated as A when it was 60 N or less, evaluated as B when it exceeded 60 N and was 70 N or less, and evaluated as C when it exceeded 70 N.

[0185] Regarding the conductor adhesion force, it was evaluated as A when it was 30 N or less, evaluated as B when it exceeded 30 N and was 50 N or less, and evaluated as C when it exceeded 50 N.

[0186] Regarding the comprehensive determination, for the evaluations of the above-described repulsive force and conductor adhesion force, with A being 3 points, B being 2 points, and C being -1 point, when the total score was 6 points, it was evaluated as A, when it was 3 points or more and 5 points or less, it was evaluated as B, and when it was 2 points or less, it was evaluated as C.

[0187] When the comprehensive determination is A or B, it means that the adhesion force between the conductor 13 and the insulating layer 14 is appropriate, and the large-sized wire is excellent in flexibility. [Experimental Examples 5-2 to 5-6] In the insulating resin, the content ratio of the ethylene-ethyl acrylate copolymer (EEA) was set to the value shown in the column of "Content Ratio of EEA" in Table 6. The content of the ultra-low density polyethylene is the remainder in the insulating resin excluding the ethylene-ethyl acrylate copolymer (EEA), and was set to the value shown in the column of "Content of VLDPE".

[0188] Except for the above points, a large-sized wire was produced in the same manner as in Experimental Example 5-1, and the above-described evaluation was performed on the obtained large-sized wire. The evaluation results are shown in Table 6.

[0189]

Table 6

[0190] That is, it was confirmed that changing the composition of the insulating layer, specifically, for example, changing the secant modulus of the insulating layer, would cause a change in the flexibility of the thick wire.

[0191] When the insulating resin contained a polyethylene resin and the total content of the ethylene-ethyl acrylate copolymer and the polyethylene resin was 100% by mass, when the content of the ethylene-ethyl acrylate copolymer was greater than 20% by mass and less than 90% by mass, it was confirmed that the secant modulus of the insulating layer was 15 MPa or more and 41 MPa or less. And in this case, it was confirmed that all of the resilience, the evaluation of the conductor adhesion, and the overall judgment were A or B.

Explanation of Signs

[0192] 10, 20, 30, 40, 50 thick wires D10 Outer diameter of the thick wire 11 Strands D11 Strand diameter 121 First stranded wire 122 Second stranded wire 123 Third stranded wire 13, 33, 53 Conductors D13 Outer diameter of the conductor S13 Nominal cross-sectional area (calculated cross-sectional area) 14, 34, 54 Insulating layers T14 Coating thickness 35 Shielding layer 36 Outer coating 411 First fixing plate 411A Fixing surface 412 Second fixing plate 42 Fixing member 401 Flexure 402A First End 402B Second End R1, R2 Radius of Curvature A Block Arrow B Block Arrow (Longitudinal Direction of Thick Wire) L Length 500 Conductor Adhesion Measuring Fixture

Claims

1. A thick wire for an electric vehicle, comprising a conductor and an insulating layer covering the outer surface of the conductor, and being used for a high current of 100 A or more and a high voltage of 30 V or more, wherein the conductor includes a first stranded wire formed by stranding a plurality of strands, and a second stranded wire formed by stranding a plurality of the first stranded wires, the strand diameter of the strands is 0.18 mm or more and 0.35 mm or less, the secant modulus of the insulating layer is 15 MPa or more and 41 MPa or less, the conductor has a nominal cross-sectional area of 70 SQ, when the thick wire is bent at a bent portion and the radius of curvature of the bent portion is changed from 100 mm to 50 mm, the repulsive force is 55 N or less, A thick wire in which the conductor adhesion force, which is the adhesion force between the conductor and the insulating layer, is 50 N or less.

2. A thick wire for an electric vehicle, comprising a conductor and an insulating layer covering the outer surface of the conductor, and being used for a high current of 100 A or more and a high voltage of 30 V or more, wherein the conductor includes a first stranded wire formed by stranding a plurality of strands, and a second stranded wire formed by stranding a plurality of the first stranded wires, the strand diameter of the strands is 0.18 mm or more and 0.35 mm or less, the secant modulus of the insulating layer is 15 MPa or more and 41 MPa or less, the conductor has a nominal cross-sectional area of 95 SQ, when the thick wire is bent at a bent portion and the radius of curvature of the bent portion is changed from 100 mm to 50 mm, the repulsive force is 70 N or less, A thick wire in which the conductor adhesion force, which is the adhesion force between the conductor and the insulating layer, is 50 N or less.

3. A thick wire for an electric vehicle, comprising a conductor and an insulating layer covering the outer surface of the conductor, and being used for a high current of 100 A or more and a high voltage of 30 V or more, wherein the conductor includes a first stranded wire formed by stranding a plurality of strands, and a second stranded wire formed by stranding a plurality of the first stranded wires, the strand diameter of the strands is 0.18 mm or more and 0.35 mm or less, the secant modulus of the insulating layer is 15 MPa or more and 41 MPa or less, the conductor has a nominal cross-sectional area of 120 SQ, when the thick wire is bent at a bent portion and the radius of curvature of the bent portion is changed from 100 mm to 50 mm, the repulsive force is 140 N or less, A thick wire in which the conductor adhesion force, which is the adhesion force between the conductor and the insulating layer, is 50 N or less.

4. A thick wire for an electric vehicle, comprising a conductor and an insulating layer covering the outer surface of the conductor, and being used for a high current of 100 A or more and a high voltage of 30 V or more, wherein The conductor includes a first stranded wire formed by twisting a plurality of individual wires, and a second stranded wire formed by twisting a plurality of the first stranded wires. The diameter of the individual wire is 0.18 mm or more and 0.35 mm or less. The secant modulus of the insulating layer is 15 MPa or more and 41 MPa or less. The insulating layer contains an insulating resin. The insulating resin contains an ethylene-ethyl acrylate copolymer, and the wire is a large-diameter wire. **Claim 5** The large-diameter wire according to claim 4, wherein the ethylene-ethyl acrylate copolymer contains more than 10% by mass and less than 35% by mass of ethyl acrylate. **Claim 6** The insulating resin contains a polyethylene resin. When the total content of the ethylene-ethyl acrylate copolymer and the polyethylene resin is 100% by mass, the content of the ethylene-ethyl acrylate copolymer is more than 20% by mass and less than 90% by mass. The large-diameter wire according to claim 4 or claim 5. **Claim 7** The large-diameter wire according to any one of claims 1 to 6, wherein the conductor includes a third stranded wire formed by twisting a plurality of the second stranded wires.

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