JP7316838B2 - Stranded conductors and coated wires - Google Patents

Description

TECHNICAL FIELD The present invention relates to a stranded conductor and a coated wire using lightweight aluminum or aluminum alloy.

Instead of copper, aluminum and aluminum alloys, which are lighter than copper, are sometimes used as conductors for transmitting electric power. Wire conductors are used.

A covered electric wire 100 having such a stranded conductor, for example, as shown in FIG. For example, Patent Literature 1 describes a stranded aluminum wire formed by twisting together aluminum alloy wires having a tensile strength of 110 MPa or more, as an aluminum conductive wire that is lightweight, flexible, and excellent in flexibility. In addition, in Patent Document 2, a single-wire aluminum conductor, which is a soft aluminum conductor with a tensile strength of 90 to 150 MPa, is used as an aluminum electric wire that can exhibit excellent wiring workability due to excellent heat resistance and flexibility. aluminum wire is described. In addition, in Patent Document 3, as an aluminum electric wire that suppresses the deterioration of mechanical properties such as flexibility and heat resistance when used together with PVC electric wires, a base resin made of polyethylene resin and ethylene copolymer resin is used. , describes an aluminum electric wire obtained by coating an aluminum conductor with an insulating coating made of an insulating composition containing a flame-retardant metal hydrate.

JP 2006-253109 A Japanese Unexamined Patent Application Publication No. 2002-208317 JP 2012-099412 A

However, an aluminum electric wire using a stranded conductor made of aluminum or an aluminum alloy tends to return to its original shape when a force is applied in a bending direction, and tends to be difficult to bend.

In addition, in the covered electric wire 100 having a stranded conductor, the insulating layer 102 and the sheath 103 are peeled off (skinned) to expose the ends (see FIG. 11A) and intermediate portions of the stranded conductor 101. , a connection member (not shown) such as a terminal or a connector is crimped, and connected to a connection object via this connection member. However, since a passivation film with high electrical resistance is formed on the surface of a stranded conductor made of aluminum or an aluminum alloy, when the stranded conductor is connected to a connection member such as a terminal or connector, The electrical resistance sometimes increased at a portion of the connection with the stranded conductor. In particular, the connection between the connection member and the stranded conductor is generally crimped and fixed by crimping the outer surface of the connection member in which the stranded conductor is inserted. If there is, most of the passivation film formed on the surface of the stranded wire conductor exists without being destroyed, and as a result, a large amount of the passivation film remains at the connection portion, increasing the electrical resistance at the connection portion. Therefore, there is a tendency for the resistance value between wires to vary.

Here, the aluminum stranded wire described in Patent Document 1 is improved in flexibility and bendability by adjusting the composition of the aluminum alloy. However, there is no description of the connection reliability between the and the connection member. Further, the aluminum electric wire described in Patent Document 2 improves wiring workability such as flexibility by adjusting the tensile strength of a single aluminum electric wire. It does not describe the connection reliability between the sheath, the stranded conductor and the connection member. In addition, the aluminum electric wire described in Patent Document 3 suppresses deterioration of mechanical properties such as flexibility and heat resistance of the insulating coating covering the aluminum conductor. No mention is made of connection reliability between the conductor and the connection member. However, it is difficult to form a curl in these aluminum electric wires, and when the aluminum electric wires are formed from a twisted wire in which the strands are twisted together, the resistance value tends to vary between the strands. Therefore, it has been desired to develop a stranded conductor that is easy to bend and has high connection reliability with connection members.

SUMMARY OF THE INVENTION An object of the present invention is to provide a stranded conductor that is easily bent and has high connection reliability with a connection member, and a coated wire using the same.

The inventors have found that for aluminum-based strands located in a single layer or multiple layers formed around the central conductor wire of a stranded conductor, the ratio of the longitudinal dimension to the radial dimension of the stranded conductor is By constructing the unit cross section so that the average value of the aspect ratio is within a predetermined range, the stranded conductor can easily be bent and the connection reliability between the stranded conductor and the connection member can be improved. and completed the present invention based on such findings.

That is, the gist and configuration of the present invention are as follows.
(1) A stranded conductor formed by twisting a plurality of aluminum-based wires so as to form a single layer or a plurality of layers around a central conductor wire made of an aluminum-based wire, wherein the aluminum The 0.2% proof stress of the system strand is 50 to 120 MPa, and the aluminum system located in the single layer or multiple layers when viewed in the longitudinal cross section of the stranded conductor including the virtual center line of the center conductor wire A stranded conductor, wherein the strand has a unit cross section with an average aspect ratio, which is the ratio of the longitudinal dimension to the radial dimension of the stranded conductor, in the range of 4.2 to 13.0.
(2) The plurality of aluminum-based wires form a plurality of layers, and when viewed in a longitudinal cross section of the stranded conductor, two imaginary wires connecting positions corresponding to 50% of the radius of the stranded conductor With the intermediate line as a boundary line, the inner layer side region of the stranded conductor defined by the two imaginary intermediate lines in the longitudinal cross section, and the outer peripheral surface of the stranded conductor and each of the two imaginary intermediate lines. When divided into the outer layer side region of the stranded conductor divided by The stranded conductor according to (1) above, which is larger than the average value of the aspect ratios of the unit cross-sectional portions of the strands.
(3) Aluminum positioned in two layers adjacent to each other in the radial direction of the stranded conductor, among the plurality of aluminum-based strands forming the plurality of layers, when viewed in a cross section in the longitudinal direction of the stranded conductor In the aluminum-based wires, two or more second unit cross-sectional portions of the aluminum-based wires positioned radially outward overlap with respect to one first unit cross-sectional portion of the aluminum-based wires positioned radially inward. The longitudinal center position of the second unit cross-section portion that is in a positional relationship and has the largest longitudinal overlap ratio with the first unit cross-section portion among the two or more second unit cross-section portions is the second unit cross-section portion. The stranded conductor according to (2) above, which is within a dimension range corresponding to 35% of the longitudinal dimension of the first unit cross section from the longitudinal center position of one unit cross section.
(4) The stranded conductor has an arithmetic mean height (Sa) of 0 on the surface portion of the outermost layer aluminum-based strand located in the outermost layer, which forms the outer peripheral surface of the crimped portion to which the connection member is crimped. The stranded conductor according to any one of (1) to (3) above, which has a roughened region of 4 μm or more and 500 μm or less.
(5) The outermost layer aluminum-based wire is a round wire or a flat wire, and the ratio of the maximum wire diameter to the minimum wire diameter of the crimped portion is 1.1 or more and 2.0 or less on average. The stranded conductor according to (4) above.
(6) When the stranded conductor is loaded with a load on a cylindrical winding jig, wound, and then unloaded, the load required to give the stranded conductor a bending habit with a curvature radius of 110 mm is The stranded conductor according to any one of (1) to (5) above, wherein the stranded conductor has a cross-sectional area of α [mm ² ] of 0.025α[N] or less.
(7) A coated electric wire comprising the stranded conductor according to any one of (1) to (6) above and an insulating coating formed on the outer peripheral surface of the stranded conductor.
(8) The coated wire according to (7) above and a connection member crimped and fixed to the coated wire, wherein the standard deviation σ of the resistance value between the aluminum-based wire and the connection member is the above A coated wire with a connecting member, the resistance value of which is 25% or less of the average.

According to the present invention, the aluminum-based strand has a unit cross-section having an average aspect ratio within a predetermined range when viewed in a cross section in the longitudinal direction including the virtual center line of the central conductor wire of the stranded conductor. , a stranded wire conductor that is easy to bend and has high connection reliability with a connection member even when an aluminum-based strand with a large 0.2% yield strength is used, and a coating using the same Wires can be provided.

1 shows an example of the configuration of a covered electric wire having a stranded conductor according to an embodiment of the present invention, where (a) is a front view, and (b) is a cut of the covered electric wire shown in (a) on the II line. (c) is a cross-sectional view of the covered electric wire shown in (b) cut along line II-II. FIG. 2 is a cross-sectional view showing the crimped portion of the stranded conductor according to the embodiment of the present invention, showing the minimum wire diameter and the maximum wire diameter of the strands constituting the stranded conductor in a (compressed) state before being crimped. is shown. FIG. 4 is a front view showing an example of the twisting direction of adjacent layers in the stranded conductor according to the embodiment of the present invention, where the twisting directions of the strands located in the adjacent layers are in the crossing direction (reverse winding). indicates BRIEF DESCRIPTION OF THE DRAWINGS It is a perspective view which shows an example of a principal part structure of the covered electric wire with a terminal which concerns on embodiment of this invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing an example of a configuration of a main part of a coated branch wire according to an embodiment of the present invention; BRIEF DESCRIPTION OF THE DRAWINGS It is a perspective view which shows an example of a principal part structure of the covered electric wire with an auxiliary wire which concerns on embodiment of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a perspective view which shows an example of a principal part structure of the covered branch electric wire with a terminal which concerns on embodiment of this invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing an example of a configuration of a main part of a covered branch electric wire with an auxiliary wire according to an embodiment of the present invention; It is a figure which shows an example of the cross section of the twisted wire conductor which concerns on the example of this invention. It is a schematic diagram showing the evaluation method of the force to form a bending habit in the example of the present invention, in which (a) is the state before forming the bending habit, and (b) is the state when a load is applied to form the bending habit. indicates 1 shows an example of the configuration of a covered electric wire having a stranded conductor according to the prior art, (a) is a front view, and (b) is a view of the covered electric wire shown in (a) cut along line III-III. It is a sectional view.

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. In addition, the present invention is not limited to the following embodiments, and various modifications are possible without changing the gist of the present invention.

<Twisted wire conductor>
The stranded conductor of the present embodiment is a stranded conductor formed by twisting a plurality of aluminum-based strands so as to form a single layer or a plurality of layers around a central conductor wire made of an aluminum-based strand. wherein the aluminum-based strand has a 0.2% proof stress of 50 to 120 MPa, and the single layer or the plurality of layers when viewed in a longitudinal cross section of the stranded conductor including the virtual center line of the central conductor wire The aluminum-based strand located at 1 has a unit cross-sectional portion in which the average value of the aspect ratio, which is the ratio of the longitudinal dimension to the radial dimension of the stranded conductor, is in the range of 4.2 to 13.0.

In the stranded conductor according to the present embodiment, the longitudinal dimension of the aluminum-based strands positioned in a single layer or multiple layers formed around the central conductor wire of the stranded conductor is By constructing the unit cross section so that the average value of the aspect ratio, which is the ratio of Therefore, even if an aluminum-based wire with a large 0.2% proof stress is used, it is possible to easily give a bending tendency to the stranded conductor, and between a connection member such as a terminal and a connector. connection reliability can be improved.

Hereinafter, embodiments of the present invention will be described in detail.

<Embodiment of stranded conductor>
FIGS. 1(a) and 1(b) show an example of the configuration of a covered electric wire 1 having a stranded conductor 10 according to this embodiment. FIG. 1(a) is a front view, and FIG. 1(b). is a cross-sectional view of the coated wire shown in FIG. 1(a) cut along the II line, and FIG. 1(c) is a cross-sectional view of the coated wire shown in FIG. 1(b) cut along the II-II line. is. The stranded conductor 10 according to the present embodiment is formed by twisting a plurality of aluminum-based wires 121 and 122 so as to form a single layer or a plurality of layers around a central conductor wire 11 made of an aluminum-based wire. When viewed in a longitudinal cross section, which is a cross section in the longitudinal direction E of the stranded conductor 10 including the virtual center line O of the central conductor wire 11, the aluminum-based _The strands 121 and 122 have dimensions X ( _{X 1} , X ₂ , _{X 3 ,} ) has an average value of aspect ratios in the range of 4.2 to 13.0 (first unit cross section 123, second unit cross section 124). In the following, the covered electric wire 1 having the stranded conductor 10 having a two-layer twist structure shown in FIG. 1 will be described as an example. It may have a stranded conductor with a twist structure of three or more layers.

[Aluminum-based strand and its unit cross section]
Examples of the aluminum-based strands forming the stranded conductor 10 include strands made of pure aluminum or an aluminum alloy. Among these, aluminum-manganese alloys, aluminum-magnesium alloys, aluminum-magnesium-silicon alloys, aluminum-zinc-magnesium alloys, aluminum-copper-magnesium alloys, and the like can be used as aluminum alloys.

Here, as the aluminum-based strands, those having a 0.2% proof stress of 50 to 120 MPa can be used. The stranded conductor 10 of the present invention has a large 0.2% yield strength, and can easily be given a desired bending habit even when aluminum-based strands that are difficult to plastically deform are used. Here, it is more preferable to use an aluminum-based wire having a 0.2% yield strength of 50 to 115 MPa.

The aluminum-based element wires constituting the stranded conductor 10 according to the present embodiment include a central conductor wire 11 and a plurality of aluminum-based elements so as to form a single layer or a plurality of layers around the central conductor wire 11. The wires 121 and 122 are roughly divided into outer wires 12 formed by twisting wires 121 and 122 together.

Here, when a plurality of layers are formed in the stranded conductor 10, the outer strand 12 is viewed in a longitudinal cross section of the stranded conductor including the virtual center line O which is the center line of the center conductor wire 11, The outer wire 12 is formed with two imaginary intermediate lines C (FIG. 1(c)) connecting positions corresponding to 50% ((1/2)r) of the radius r of the stranded conductor as boundary lines. A plurality of layers can be considered by dividing them into an inner layer side region 15 and an outer layer side region 16 . Specifically, when viewed in the longitudinal section of the stranded conductor 10 including the virtual center line O of the central conductor wire 11, the longitudinal section of the stranded conductor 10 is divided by two virtual intermediate lines C. It can be divided into a side region 15 and an outer layer side region 16 of the stranded conductor defined by each of the two virtual intermediate lines and the outer peripheral surface of the stranded conductor. Here, the inner layer side region 15 is a region inside the stranded conductor 10 in the radial direction D, and the outer layer side region 16 is a region outside the stranded conductor 10 in the radial direction D. adjacent to the outside. Note that when the imaginary intermediate line C crosses the inside of the unit cross section like the unit cross section 123 shown in FIG. (also referred to as being located in the inner layer side region 15). Further, even when the outer wire 12 of the stranded conductor 10 is a single layer, the unit cross section formed by the outer wire 12 is included in the inner layer side region 15 (also referred to as being located in the inner layer side region 15). shall be

Among these, the inner layer side region 15 of the stranded conductor 10 has a plurality of inner layer aluminum-based strands 121 constituting the inner layer, and each inner layer aluminum-based strand 121 is located on the virtual center line of the central conductor wire 11. When viewed in the longitudinal cross section of the stranded conductor 10 including O, it appears that the plurality of first unit cross-sectional portions 123 are arranged along the longitudinal direction E of the stranded conductor 10 . In addition, the outer layer side region 16 has a plurality of outer layer aluminum-based wires 122 constituting the outer layer, and each outer layer aluminum-based wire 122 is a stranded conductor including the virtual center line O of the central conductor wire 11. 10 , it appears that a plurality of second unit cross-sectional portions 124 are aligned along the longitudinal direction E of the stranded conductor 10 .

The term "unit cross-section" as used herein refers to a cross-section obtained by cutting each of the twisted aluminum-based strands other than the central conductor wire constituting the stranded conductor 10 in the longitudinal direction of the stranded conductor 10. In other words, the cross-sectional shape, relative position, and the like can be appropriately set depending on the wire diameter, twist pitch, twist direction, and the like of the wire.

In the stranded conductor 10 according to the present embodiment, the aluminum-based strands positioned in a single layer or a plurality of layers, that is, the outer strands 12 have a radial dimension W (W ₁ , W ₂ , W ₃ . The average of the aspect ratios X/W (X1/ _W1 , _X2 / _W2 , _X3 / _W3 ...) which is the ratio of the longitudinal dimensions X ( _X1 , _X2 , _{X3 ...} ) It has a unit cross section with a value in the range of 4.2 to 13.0. More preferably, the average value of the aspect ratios (X ₁ /W ₁ ) of the unit cross sections (for example, the first unit cross sections 123 in FIG. 1(c)) formed by the inner layer aluminum-based strands 121 is 4.2. configured to be in the range of ~13.0. When the aspect ratio is within the above range, the stranded conductor can be easily bent, and the connection reliability with the connection member can be improved.

The average value of the aspect ratio X/W in the present invention is obtained when the aluminum-based wires 121 and 122, which are the plurality of outer wires 12, are twisted together so as to form a plurality of layers around the central conductor wire 11. , the average value (U) of the aspect ratios of the unit cross-sections (for example, the second unit cross-sections 124a and 124b in FIG. 1(c)) composed of aluminum-based wires located in the outer layer side region 16, and the inner layer side region 15 (for example, the first unit cross section 123 in FIG. 1(c)), the arithmetic average of the aspect ratios (I) obtained respectively. ((U+I)/2). On the other hand, in a stranded conductor (not shown) in which a plurality of aluminum-based wires are twisted together so as to form a single layer around the central conductor wire 11, the twisted aluminum-based wires (inner layer side region 15) is the average value of the aspect ratios of the unit cross-sections. Note that the average value (U) and the average value (I) described above can each be an average value of five sample cross sections.

Further, in the stranded conductor 10 according to the present embodiment, the reaction force is relieved by the entire stranded conductor, and the engagement between the strands is facilitated, thereby making it easier to form a bending habit. The average value (U) of the aspect ratios of the unit cross sections (for example, the second unit cross sections 124a and 124b in FIG. 1(c)) composed of the aluminum-based wires located in the inner layer side region 15, and the aluminum located in the inner layer side region 15 The ratio of the average value (I) of the aspect ratio of the unit cross section (for example, the first unit cross section 123 in FIG. 1(c)) formed by the system strands (the average value (I) of the aspect ratio/the ratio of the aspect ratio The average value (U) is preferably 0.8 or more and 1.5 or less. Furthermore, the average value I of the aspect ratios of the unit cross-sectional portions of the aluminum-based wires located in the inner layer side region 15 is higher than the average value U of the aspect ratios of the unit cross-sectional portions of the aluminum-based wires located in the outer layer side region 16. is preferably large.

In the stranded conductor 10 according to the present embodiment, the lower limit of the average value of the aspect ratios of the unit cross-sectional portions composed of the aluminum-based strands located in both the inner layer side region 15 and the outer layer side region 16 is the reaction force. It is 4.2 or more, preferably 4.5 or more, in order to relax the stranded conductor as a whole and facilitate engagement between strands to make it easier to bend. On the other hand, in the stranded conductor 10 according to the present embodiment, the upper limit of the average value of the aspect ratios of the unit cross sections formed by the aluminum-based strands located in the inner layer side region 15 and the outer layer side region 16 is It is 13.0 or less, preferably 10.0 or less, in order to suppress variations in the wire resistance value by facilitating destruction of the oxide film by the wires rubbing against each other.

In addition, in the stranded conductor 10 according to the present embodiment, the lower limit of the average aspect ratio of the unit cross section formed by the aluminum-based strands located in the inner layer side region 15 relaxes the reaction force in the entire stranded wire. It is preferably 4.5 or more, more preferably 5.0 or more, in order to make it easier to form a bending habit by facilitating engagement between the strands. On the other hand, in the stranded conductor 10 according to the present embodiment, the upper limit of the average value of the aspect ratios of the unit cross-sectional portions formed by the aluminum-based strands located in the inner layer side region 15 is such that the adjacent strands rub against each other. It is preferably 12.0 or less, and more preferably 10.0 or less, in order to suppress variations in the wire resistance value by facilitating destruction of the oxide film.

Among the stranded conductor 10 according to the present embodiment, among the plurality of aluminum-based strands 121 and 122 forming a plurality of layers when viewed in longitudinal cross section, The aluminum-based wires respectively positioned in the two adjacent layers constituting the inner layer side region 15 and the outer layer side region 16, for example, the inner layer aluminum-based wire 121 and the outer layer aluminum-based wire 122, are located in the inner layer positioned radially inward. Two or more second unit cross-sectional portions (in FIG. 1C, two It is preferable that the second unit cross-sectional portions 124a and 124b) have a positional relationship in which they overlap. At this time, of the two or more second unit cross-sectional portions of the aluminum-based wire positioned on the outer layer side, the second unit cross-sectional portion having the largest overlapping ratio in the longitudinal direction E with the first unit cross-sectional portion 123 (Fig. 1 In (c), the longitudinal center position P2 of the second unit cross section 124a) corresponds to ₃₅ % of the longitudinal dimension X1 of the first unit cross section 123 from the longitudinal center position P1 of the first unit cross section 123. It is preferably within the range to the position P of the dimension _0.35X1 . Thus, the dimension d from the longitudinal center position P1 of the first unit cross section 123 to the longitudinal center position P2 of the second unit cross section 124a is the dimension position from the longitudinal center position P1 of the first unit cross section 123. By being within the range up to P, the contacting portions of the wires on the inner layer side and the outer layer side rub against each other and the oxide film is easily destroyed, so that the connection reliability with the connecting member can be improved.

The average value of the aspect ratios of the unit cross-sectional portions of the aluminum-based wires located in the inner layer side region 15 (for example, the first unit cross-sectional portion 123 in FIG. 1(c)) and the aluminum-based wires located in the outer layer side region 16 The average value of the aspect ratios of the unit cross-sections (for example, the second unit cross-sections 124a and 124b in FIG. 1(c)) is measured from the longitudinal center position P1 of the first unit cross-section 123 to the longitudinal center of the second unit cross-section 124. The dimension d up to the position P2 can be appropriately adjusted by adjusting the strength of twisting of the aluminum-based strands and the twisted wire compression rate when compressing the twisted aluminum-based strands to obtain the stranded conductor 10. value can be adjusted.

[Roughened area]
Of the outer-layer aluminum-based wires 122 of the stranded conductor 10 according to the present embodiment, the outermost-layer aluminum-based wires 126 in the outermost layer include the terminal 30 (see FIG. 4), the branch connector 41 (see FIG. 5), the extension In order to form the outer peripheral surface of the crimped portion to which a connecting member such as the connector 52 (see FIG. 6) is crimped, the surface portion including the crimped portion has an arithmetic mean height (Sa) of 0.4 μm or more and 500 μm or less. It is preferred to have a roughened region 2 of By having the roughened region 2 having an arithmetic mean height (Sa) within such a numerical range, many of the convex portions in the uneven shape forming the roughened region 2 are connected members ( (not shown)), and many of the deformed portions are electrically connected to the connection member without being in contact with the atmosphere. Formation of a passivation film at the connecting portion between the stranded conductors 10 is greatly suppressed, and an increase in electrical resistance between the stranded wire conductor 10 and the connecting member can be greatly suppressed. That is, when the stranded conductor 10 has the roughened region 2 having the arithmetic mean height (Sa) within the above numerical range, in addition to the ease of bending and high connection reliability with the connection member, Since an increase in electrical resistance at the connection portion can be greatly suppressed, even a twisted wire conductor having a bending habit can be greatly suppressed from a decrease in conductivity at the connection portion.

Here, the arithmetic mean height (Sa) of the roughened region 2 of the outermost aluminum-based strands 126 constitutes the outer surface of the stranded conductor 10 of one of the outermost aluminum-based strands 126. It is the arithmetic mean height (Sa) of the roughened region 2 measured with respect to the surface of the wire, with a square region having a side length of 1/3 of the wire diameter of the wire as a reference plane. From the viewpoint of suppressing an increase in electrical resistance between the stranded conductor 10 and the connecting member, the lower limit of the arithmetic mean height (Sa) is more preferably 6.0 μm, more preferably 9.0 μm. The upper limit of the thickness (Sa) is more preferably 350 µm, and even more preferably 50 µm.

In addition, the longitudinal dimension Z, which is the dimension in the longitudinal direction E of the stranded conductor 10, of the roughened region 2 suppresses an increase in the electrical resistance of the entire connecting portion in contact with the connecting member. It is preferably equal to or greater than the longitudinal dimension. Here, the longitudinal dimension of the connection member is the dimension in the direction corresponding to the longitudinal direction E of the stranded conductor 10 . More specifically, the longitudinal dimension Z of the roughened region 2 is preferably in the range of, for example, 10 mm or more and 300 mm or less.

In particular, when the stranded conductor 10 is a compressed stranded conductor obtained by applying compression, the cross section of the outer strand 12, for example, the outermost aluminum-based strand 126, as shown in FIG. It is preferable that the portion to be crimped is compressed, and the ratio of the maximum wire diameter L2 to the minimum wire diameter L1 of the crimped portion (before crimping) (maximum wire diameter L2/minimum wire diameter L1) is The arithmetic mean is preferably 1.1 or more and 2.0 or less. Here, regarding the cross section of the outermost layer aluminum-based wire 126, by setting the ratio of the maximum wire diameter L2 to the minimum wire diameter L1 of the crimped portion to be in the range of 1.1 or more and 2.0 or less on average, the outermost layer Since the contact area between the aluminum-based strands 126 and the connection member increases, and the arithmetic mean height (Sa) described above makes it possible to achieve further electrical connection between the stranded conductor 10 and the connection member, the connection The connection reliability between members can be further improved.

The method of forming the roughened region 2 in the stranded conductor 10 is not particularly limited, but for example, aluminum-based strands are twisted around the central conductor wire 11 to form the outer strand 12 of a single layer or two or more layers. After that, of the outermost layer aluminum-based wire 126, a roughened region 2 is manually formed using a roughening member such as a stainless brush for the portion to which the connection member is crimped, that is, the crimped portion, or , a roughening machine with this roughening member can be used to form the roughened region 2 .

Here, the arithmetic mean height (Sa) of the roughened region 2 can be adjusted to an appropriate value by adjusting the conditions for forming the roughened region 2 . For example, when the roughened region 2 is formed using a stainless steel brush, the wire diameter and wire density of the brush, and the load and the number of times of rubbing the outermost aluminum-based wire 126 can be adjusted.

In addition, regarding the ratio of the maximum wire diameter to the minimum wire diameter in the cross section of the outermost aluminum-based wire 126, the flatness (wire flatness) and shape of the aluminum-based wire, and the twisted aluminum-based wire are compressed. An appropriate value can be obtained by adjusting the stranded wire compression rate when obtaining the stranded wire conductor 10 by means of the following.

[Shape, etc. of aluminum-based wire]
The inner-layer aluminum-based strands 121 and the outer-layer aluminum-based strands 122 are preferably round wires or flat wires because they can stably form a contact portion with the connection member and the stranded conductor 10 can be easily bent. .

The wire diameters of the inner layer aluminum-based wire 121 and the outer layer aluminum-based wire 122 are not particularly limited, but the lower limit thereof is preferably 1.0 mm, more preferably 1.5 mm, from the viewpoint of preventing disconnection due to wear or the like. On the other hand, the upper limit of the wire diameters of the inner layer aluminum-based wire 121 and the outer layer aluminum-based wire 122 is preferably 3.2 mm, more preferably 3.0 mm, from the viewpoint of providing desired bending workability. 5 mm is more preferred.

In this specification, the wire diameter (wire diameter) of an aluminum-based wire having a non-circular cross section such as a flat wire is obtained by converting the wire diameter from the cross-sectional area of a round wire having the same cross-sectional area. . Similarly, the wire diameter of the outermost layer aluminum-based strands 126 in the compressed stranded conductor that has been subjected to compression is similarly obtained by converting the cross-sectional area of a round wire having the same cross-sectional area into the wire diameter.

Here, the wire diameter of the inner layer aluminum-based wire 121 may be the same as or different from the wire diameter of the outer layer aluminum-based wire 122 .

In the stranded conductor 10 according to the present embodiment, the aluminum-based aluminum-based wires located in adjacent layers (for example, the inner-layer aluminum-based wire 121 and the outer-layer aluminum-based wire 122 in FIG. 1) are adjacent to each other in the radial direction D of the stranded conductor. It is preferable that the strands have an arrangement relationship such that the twist directions intersect each other. At this time, by intersecting the twist directions of adjacent layers, the portions of the strands that are in point contact rub against each other strongly and become difficult to move, so that the stranded conductor 10 can be easily given a bend. Further, by intersecting the twisting directions of adjacent layers, the stranded conductor 10 has a radial cross section closer to a circular shape, and the stranded conductor 10 can be stably crimped to the connection member. In addition, by crossing the twist directions of adjacent layers, the aluminum-based wires forming the outermost layer and the aluminum-based wires forming the adjacent inner layer are arranged so as to be in point contact with each other. The portions of the wires that are in contact rub against each other, making it easier for the oxide film to break, resulting in improved connection stability.

Here, the arrangement relationship in which the twist directions intersect is, for example, aluminum-based wires located in adjacent layers, such as the stranded conductor 10 shown in FIG. The arrangement relationship (reverse winding) is preferable so that the twist directions of the aluminum-based wires 122 and the inner-layer aluminum-based wires 121 intersect each other (reverse directions). The twist directions may be crossed by giving a difference in strength to the twist of the wire. Further, the arrangement relationship (parallel winding) may be such that the twisting directions of the aluminum-based strands located in adjacent layers are the same (substantially parallel) to each other.

FIG. 1 shows a case where the central conductor wire 11 constituting the stranded conductor 10 according to the present embodiment is composed of one element wire. It may consist of lines. Here, when the central conductor wire 11 is composed of a central twisted wire obtained by twisting a plurality of strands, the central axis of the central twisted wire obtained by twisting a plurality of strands is assumed to be the virtual center line O of the central conductor wire. be able to. In addition, it is preferable that the twist directions of the central twisted wire and the strands positioned in the adjacent outer layer cross each other as described above.

The stranded conductor 10 according to the present embodiment has a bending tendency with a radius of curvature of 110 mm when the stranded conductor 10 according to the present embodiment is wound with a load applied to a cylindrical winding jig and then unloaded. The load is preferably 0.025α[N] or less, where α[mm ² ] is the cross-sectional area of the stranded conductor 10 . Such a stranded conductor 10 is difficult to return to its original shape when force is applied in the bending direction, and tends to be bent. In particular, in the stranded conductor 10 according to the present embodiment, even when aluminum-based strands having a large 0.2% yield strength are used, it is possible to easily form a bending habit. Here, it is more preferable that the load required to give the stranded conductor 10 a bending habit with a radius of curvature of 110 mm is 0.010α[N] or less. The radius of the cylindrical winding jig can be set to, for example, 50 to 109 mm from the viewpoint of easily giving the stranded conductor 10 a bend.

<Embodiment of Covered Wire>
The covered electric wire 1 according to the present embodiment has the above-described stranded conductor 10 and an insulating coating 13 formed on the outer peripheral surface portion of the stranded conductor 10, as shown in FIG. 1, for example. Here, from the viewpoint of improving connection reliability between the stranded conductor 10 and the connection member, the covered electric wire 1 is formed on the stranded conductor 10 and the outer peripheral surface portion of the stranded conductor 10 excluding the roughened region 2. It is preferable to have an insulating coating 13 with a More specifically, at least the insulating coating 13 is laminated on the outer circumference of the stranded conductor 10, and more preferably, the sheath 14 is laminated on the outer circumference as the outermost layer.

Here, as the insulating coating 13, a known material can be used, for example, polyolefin such as polyethylene and polypropylene, and polyvinyl chloride can be used. In addition, in order to prevent the insulating coating 13 from being damaged by the roughened region 2 , the insulating coating 13 is preferably formed on the outer peripheral surface portion of the stranded conductor 10 excluding the roughened region 2 .

<Embodiments of Covered Wire with Terminal, Covered Branch Wire, and Covered Wire with Complementary Wire>
In the covered electric wire 1 according to the present embodiment, connection members such as a terminal, a branch connector, and an extension connector are preferably crimped to the stranded conductor 10, thereby forming a covered electric wire with a terminal, a covered branch electric wire, and a covered electric wire with an auxiliary wire. It is preferable to constitute an electric wire. From the viewpoint of improving connection reliability between the stranded conductor 10 and the connection member, it is more preferable that the connection member is crimped onto at least the roughened region 2 of the covered electric wire 1 . An example in which various connection members are crimped to the roughened region 2 of the covered wire 1 will be described below, but the connection member may be crimped to the covered wire 1 that does not have the roughened region 2 .

At this time, it is preferable that the standard deviation σ of the resistance values between the aluminum-based strands and the connection member constituting the stranded conductor 10 is 25% or less of the average resistance value. As a result, most of the passivation film formed on the surface of the stranded wire conductor is destroyed between each of the aluminum-based strands and the connection member, so that the increase in electrical resistance due to the passivation film is less likely to occur. , high connection reliability can be obtained between the stranded conductor 10 and the connection member. Here, it is more preferable that the standard deviation σ of the resistance values between each aluminum-based element wire and the connecting member is 10% or less of the average resistance value.

(coated wire with terminal)
Among them, the covered wire 3 with a terminal has the above-described covered wire 1 and a terminal 30 crimped and fixed to the roughened region 2 formed at one end or both ends of the covered wire 1, as shown in FIG. .

Here, the terminal 30 is a member made of pure aluminum or an aluminum alloy similarly to the above-described aluminum-based wire and having a tubular inner space 31 . This terminal 30 is crimped with the roughened area 2 of the stranded conductor 10 of the covered electric wire 1 being inserted into the internal space 31, and the locking portion 32 formed thereby A terminal 30 is crimped on the roughened area 2 of the coated wire 1 .

(branch covered wire)
As shown in FIG. 5, for example, the branch covered electric wire 4 includes a first covered electric wire 1 which is the above-described covered electric wire as a main line, a second covered electric wire 40 which is another covered electric wire as a branch wire, and a branch connector 41. The first crimping portion 42 of the branch connector 41 is crimped and fixed to the roughened region 2 formed in the first covered wire 1, and the second crimping portion 43 of the branch connector 41 is used to secure the second covered wire. 40 is crimped to the stripped end.

Here, the conductor material of the second coated wire 40 may be made of pure aluminum or an aluminum alloy like the above-described aluminum-based wire, or may be made of copper or stainless steel (SUS). may be made of a material different from the constituent material of the stranded conductor 10 of .

In addition, the branch connector 41 is made of pure aluminum or an aluminum alloy in the same manner as the aluminum-based wire described above, and has a first crimping portion 42 having a cylindrical inner space with both sides open and a cylindrical inner space with one side open. It is a member having a second crimping portion 43 having a space. In this branch connector 41 , the roughened area 2 of the stranded conductor 10 of the covered electric wire 1 is positioned within the first crimping portion 42 , and the peeled end portion of the second covered electric wire 40 is the second crimping portion 43 . The first crimping portion 42 is crimped and fixed to the roughened region 2 of the covered wire 1, and the second crimping portion 43 of the second covered wire 40 is crushed while being inserted into the inner space of the The branch covered electric wire 4 can be obtained by crimping and fixing the peeled one end.

(Coated wire with auxiliary wire)
For example, as shown in FIG. 6, the covered electric wire 5 with supplementary wire includes a first covered electric wire 1 which is the above-described covered electric wire and a third covered electric wire which is another covered electric wire which is an auxiliary wire extending from the first covered electric wire 1. An electric wire 50 and an extension connector 52 are provided, and a third crimp portion 53 of the extension connector 52 is crimped and fixed to the roughened region 2 formed on the first covered electric wire 1 , and a fourth It can be obtained by crimping and fixing to the stripped end of the third coated wire 50 at the crimping portion 54 .

Here, the conductor material of the third coated wire 50 is preferably a material that is less likely to form a passive film having a higher electric resistance than the aluminum-based wire, such as copper and stainless steel (SUS).

The extension connector 52 is made of pure aluminum or an aluminum alloy like the aluminum-based wire described above, and is a member having a third crimping portion 53 and a fourth crimping portion 54 having a cylindrical inner space. In this extension connector 52 , the roughened area 2 of the stranded conductor 10 of the covered electric wire 1 is inserted into the third crimping portion 53 , and the peeled end portion of the third covered electric wire 50 is inserted into the fourth crimping portion 54 . The third crimping portion 53 is crimped and fixed to the roughened region 2 of the coated wire 1 and the fourth crimping portion 54 is pressed against the skin of the third coated wire 50 . By crimping and fixing to the stripped one end, a covered electric wire 5 with an auxiliary wire, which is an extension of the covered electric wire 1, can be obtained.

(Structure with multiple connection members)
In this embodiment, two or more of the terminals 30, the branch connectors 41 and the extension connectors 52 may be combined, and one or more of the terminals 30, the branch connectors 41 and the extension connectors 52 may be used in plurality.

For example, as shown in FIG. 7, using the first covered electric wire 1 which is the above-described covered electric wire, the first covered electric wire 1, the second covered electric wire 40 which is another covered electric wire as a branch wire, and the branch connector 41 , a terminal-equipped covered covered electric wire 6 having terminals 30 and 30' can be constructed. In this terminal-attached covered branch wire 6 , the roughened region 2 formed in the first covered wire 1 is crimped and fixed at the first crimping portion 42 of the branch connector 41 , and the second crimping portion of the branch connector 41 is crimped and fixed. 43 is crimped and fixed to the stripped end of the second coated wire 40 . On the other hand, a roughened region 2' is formed at one end of the above-described first covered wire 1, and a terminal 30 is crimped and fixed to this roughened region 2'. A roughened region 2'' is formed at the other end of the first coated wire 1, and a terminal 30' is crimped and fixed to the roughened region 2''.

Further, as shown in FIG. 8, the first covered electric wire 1 which is the above-described covered electric wire is used, the first covered electric wire 1, the second covered electric wire 40 which is another covered electric wire as a branch wire, and the branch connector 41. , third covered electric wires 50, 50', which are additional covered electric wires extending from the first covered electric wire 1, and extension connectors 52, 52'. You can also In this covered branched electric wire 7 with supplementary wires, the roughened region 2 formed in the first covered electric wire 1 is crimped and fixed at the first crimping portion 42 of the branch connector 41 , and the second crimping of the branch connector 41 is performed. At the portion 43, the stripped end of the second coated wire 40 is crimped and fixed. On the other hand, a roughened area 2' is formed at one end of the first covered wire 1, and the roughened area formed on the first covered wire 1 is formed at the third crimping portion 53 of the extension connector 52. While the region 2 ′ is crimped and fixed, the peeled one end of the third coated wire 50 is crimped and fixed to the fourth crimp portion 54 of the extension connector 52 . A roughened region 2'' is formed at the other end of the first covered wire 1, and the roughened region 2'' formed on the first covered wire 1 is formed at the third crimping portion 53' of the extension connector 52'. The flattened region 2'' is crimped and fixed, and the stripped end of the third coated wire 50' is crimped and fixed to the fourth crimp portion 54' of the extension connector 52'.

Examples of the present invention will now be described, but the present invention is not limited to these examples as long as the gist of the present invention is not exceeded.

(1) Preparation of stranded conductor and covered electric wire [Invention example 1]
As an aluminum-based wire, a round wire with a wire diameter of 1.6 mm (wire flatness = 1), material type A1070, temper symbol H11 (0.2% yield strength (described as “yield strength” in the table): Using 19 pure aluminum conductor wires of 50 (N)), six strands are twisted around one central conductor wire to form an inner layer aluminum-based strand, and 12 strands are wound around it. The wires were twisted together to form an outer layer aluminum-based element wire (outermost layer aluminum-based element wire) to produce a stranded conductor having a 1+6+12 twist structure. At this time, the outer layer aluminum-based strands were twisted together in the opposite direction to the adjacent inner layer aluminum-based strands (reverse winding). The entire stranded wire was compressed with a force that gave a compression rate (twisted wire compression rate) of 2% to obtain a compressed stranded conductor. The stranded cross-sectional area (cross-sectional area of the stranded conductor) of the resulting compressed stranded conductor is 38 mm ² .

A stainless steel brush with a strand diameter of 0.6 mm and a strand density of 1/mm ² is used in a range of 50 mm from the end of the stranded conductor, and the outermost layer located in the part where the roughened area of the stranded conductor is formed The outermost layer of the stranded conductor is moved (rubbed) five times along the longitudinal direction E of the stranded conductor with a stainless steel brush to which a load of 5 N is applied to the outer peripheral surface of the aluminum-based strand. A roughened region having a dimension Z of 50 mm along the longitudinal direction E of the stranded conductor was formed on the surface portion of the outer layer aluminum-based strand located at . For the formed roughened region, using Keyence's VK-X250, one of the outer layer aluminum-based strands located in the outermost layer of the stranded conductor, the strand constituting the outer surface of the stranded conductor Regarding the surface, the arithmetic mean height (Sa) was measured at a magnification of 400 when a square area having a side length of 1/3 of the wire diameter of the wire as a reference plane was 9.7 μm. there were.

In addition, the longitudinal section of this stranded conductor was observed using an inverted metallurgical microscope (equipment name: GX71, manufactured by OLYMPUS). , the average value of five sample cross sections was found to be 4.5. Further, when the average value of the five sample cross sections was calculated for the aspect ratio of the second unit cross section 124 in the outer layer side region, it was found to be 4.0. A simple average of the aspect ratio of the first unit cross section 123 in the inner layer side region and the aspect ratio of the second unit cross section 124 in the outer layer side region was found to be 4.25. Furthermore, for the first unit cross-section portion 123 and the second unit cross-section portion 124a having the largest longitudinal overlap ratio with this first unit cross-section portion 123, 35% of the longitudinal dimension _X1 of the first unit cross-section portion 123 The ratio (d/0.35X ₁ ) of the dimension d from the longitudinal center position P1 of the first unit cross section 123 to the longitudinal center position P2 of the second unit cross section 124a to the dimension 0.35X ₁ corresponding to When asked, it was found to be 0.9.

In addition, for this stranded conductor, a cross section perpendicular to the longitudinal direction of the stranded conductor was observed using an inverted metallurgical microscope (device name GX71, manufactured by OLYMPUS). When the ratio of the maximum wire diameter L2 to the minimum wire diameter L1 of the system wire was obtained, the arithmetic mean for each wire was found to be 1.1.

As an aluminum-based terminal to be connected to this stranded conductor, a surface coating is formed by laminating a nickel layer with a thickness of 3 μm and a tin layer with a thickness of 10 μm in the above order on the inner surface and the outer surface of a pure aluminum terminal, respectively. An aluminum-based terminal was used. The longitudinal dimension of the conductor crimping portion of this aluminum-based terminal is 8 mm. Crimping conditions such that the roughened area of the stranded conductor is inserted into the aluminum-based terminal, and the area of the crimped area where the area reduction rate is 5 to 15% is 1 to 2 times the cross-sectional area of the stranded conductor. , the stranded wire conductor was crimped to the aluminum-based terminal by crimping.

[Invention Examples 2 to 11 and Comparative Examples 1 to 3]
A compressed stranded conductor having a roughened region was obtained in the same manner as in Inventive Example 1, except that the conditions were adjusted based on the description in Table 1. The arithmetic mean height (Sa) of the roughened region of the obtained compressed stranded conductor, the ratio of the dimension d to the dimension 0.35X ₁ (d/0.35X ₁ ), the minimum of the outermost aluminum-based strand Table 1 shows the measurement results of the ratio of the maximum wire diameter to the wire diameter (L2/L1 ratio).

FIG. 9 shows a photomicrograph of a longitudinal section of the compressed stranded conductor obtained in Inventive Example 3, observed using an inverted metallographic microscope (device name: GX71, manufactured by OLYMPUS).

(2) Evaluation of the force required to impart a bending habit The resulting stranded conductor was provided with an insulating coating made of crosslinked polyethylene with a thickness of 2.0 mm and a sheath made of vinyl chloride with a thickness of 1.5 mm. The coated electric wire 1 was evaluated for the force required to form a bend. After fixing one end of the coated electric wire 1 to be evaluated to a fixing jig 8 as shown in FIG. The center axis of the shape intersects the center axis of the insulated wire 1 at a right angle when viewed from the top projection view, and the winding jig 9 presses the insulated wire 1 from above. It was fixed to the Next, at a position 0.5 m away from the winding jig 9, a load in the range of 0.1 [N] to 10 [N] is applied to the coated wire 1 from below, and as shown in FIG. , the covered electric wire 1 was bent so as to be wound around the winding jig 9, and the radius of curvature of the bent portion after unloading was measured. According to the value of the curvature radius to be measured, the load is adjusted so that the curvature radius becomes 110 mm. We found the load required to create a bending habit. The results were evaluated according to the following criteria. Table 2 shows the results.
◎: The load required to impart a bending habit with a radius of curvature of 110 mm is 0.010 α [N] or less, where α [mm ² ] is the cross-sectional area of the stranded conductor. A load required to impart a bending habit of curvature is more than 0.010α[N] and not more than 0.025α[N] when the cross-sectional area of the stranded conductor is α[mm ² ] ×: Radius A load required to impart a bending habit with a curvature of 110 mm is greater than 0.025α[N], where α[mm ² ] is the cross-sectional area of the stranded conductor.

(3) Evaluation of variations in resistance between strands that make up a stranded conductor For a stranded conductor crimped to an aluminum-based terminal, the twisted conductor was untwisted to maintain crimping to the aluminum-based terminal. After dividing into each, the electrical resistance value between all the wires and the aluminum-based terminal was measured by a 4-terminal resistance measurement method using a 3560 AC milliohm high tester (manufactured by Hioki), and the measured electrical resistance value Then, the average value and standard deviation of the electrical resistance values excluding the resistance value of the electric wire portion were calculated and evaluated according to the following criteria. Table 2 shows the results.

Here, when the standard deviation of the electrical resistance values between all the wires and the aluminum-based terminal was within 10% of the average value, it was determined that the connection reliability with the connection member was excellent in the initial period of use. "A" indicates that the standard deviation of the electrical resistance value between all the wires and the aluminum-based terminal is more than 10% and within 25% of the average value, and the connection reliability with the connection member is good at the initial stage of use. It was judged that there was, and it was set as "○". On the other hand, if the standard deviation of the electrical resistance values between all the wires and the aluminum-based terminal exceeded 25% of the average value, it was determined that the connection reliability with the connection member was inferior (impossible) in the initial period of use. and "x".

(4) Comprehensive Judgment Evaluation Method Comprehensive judgment based on the evaluation results regarding the force required to impart the bending habit and the evaluation results regarding the variation in resistance between strands was evaluated according to the following evaluation criteria. Table 2 shows the results.

Here, the evaluation results regarding the force required to create the bending habit and the evaluation results regarding the resistance variation between the strands were both evaluated as "⊚", and the easiness of creating the bending habit and the connection member. It was judged to be excellent in both high connection reliability between and was evaluated as "⊚". In addition, both the evaluation results regarding the force required to impart the bending habit and the evaluation results regarding the variation in resistance between the wires were "○" or higher, and one of the evaluation results was "◎". Those that did not have a tendency to bend were judged to be good in terms of both easiness of bending and high reliability of connection with the connection member, and were evaluated as "good". On the other hand, those evaluated as "x" in either the evaluation result regarding the force required to form the bending habit or the evaluation result regarding the resistance variation between the wires were evaluated as the ease of forming the bending habit and the connecting member. It was judged to be inferior (impossible) in at least one of the high connection reliability between and and was set as "x".

As is clear from Tables 1 and 2, aluminum-based wires having a 0.2% proof stress of 50 to 120 MPa were used, and the average aspect ratio of the unit cross-sectional portion of the aluminum-based wires was 4.2 to 13.5. In the stranded conductors in the range of 0 (Examples 1 to 11 of the present invention), both the evaluation results regarding the force required to create a bending habit and the evaluation results regarding the variation in resistance between strands were "○" or higher. In addition, since one of the evaluation results was "⊚" evaluation, it was found that both the ease of forming a bending habit and the high connection reliability with the connection member were good.

On the other hand, in the stranded conductor of Comparative Example 1 in which the average value of the aspect ratio of the unit cross section of the aluminum-based strands was as small as 2.5, the evaluation result regarding the variation in resistance between the strands was "O". , the evaluation result of the force required to form the bending habit was "x", indicating that the ease of forming the bending habit was inferior. In addition, in the stranded conductor of Comparative Example 2, in which the average value of the aspect ratio of the unit cross-sectional portion of the aluminum-based strands is as large as 19.5, the evaluation result regarding the force required to impart the bending habit was "◯". However, the evaluation result regarding the variation in resistance between the strands was "x", and the connection reliability with the connection member was inferior. In addition, in the stranded conductor of Comparative Example 3, the 0.2% yield strength of the aluminum-based strands constituting the stranded conductor was as large as 275 MPa, and although the evaluation result regarding the variation in resistance between strands was "O", The evaluation result for the force required to form the bending habit was "x", indicating that the ease of forming the bending habit was inferior.

From the above results, an aluminum-based wire having a 0.2% proof stress of 50 to 120 MPa is used, and the average aspect ratio of the unit cross-sectional portion of the aluminum-based wire is in the range of 4.2 to 13.0. Compared to the stranded conductors of Comparative Examples 1 to 3, the wire conductors (Examples 1 to 11 of the present invention) are good in both ease of bending and high connection reliability with the connection member. I found out.

Reference Signs List 1 Covered wire 2 Roughened region 3 Covered wire with terminal 4 Covered branch wire 5 Covered wire with auxiliary wire 6 Covered branch wire with terminal 7 Covered branch wire with auxiliary wire 8 Fixing jig 9 Winding jig 10 Twisted wire conductor 11 Central conductor Wire 12 Peripheral wire 13 Insulating coating 14 Sheath 15 Inner layer side area 16 Outer layer side area 30 Terminal 31 Internal space 32 Locking portion 40 Second covered wire 41 Branch connector 42 First crimping portion 43 Second crimping portion 50 Third covered wire 52 Extension connector 53 Third crimp portion 54 Fourth crimp portion 121 Inner layer aluminum-based wire 122 Outer layer aluminum-based wire 123 First unit cross-sectional portions 124, 124a, 124b Second unit cross-sectional portion 126 Outermost layer aluminum-based wire C Virtual Intermediate line D Radial direction E Longitudinal direction O Imaginary center line P1 Longitudinal center position of the first unit cross section P2 Longitudinal center position of the second unit cross section W Radial dimension of the unit cross section X Longitudinal dimension of the unit cross section Z Lengthwise dimension of roughened region L1 Minimum wire diameter L2 Maximum wire diameter d Dimension from the longitudinal center position of the first unit cross section to the longitudinal center position of the second unit cross section r Radius of stranded conductor

Claims (7)

A stranded conductor formed by twisting a plurality of aluminum-based wires so as to form a plurality of layers around a central conductor wire made of an aluminum-based wire,
The twist directions of the aluminum-based wires located in adjacent layers among the plurality of layers are arranged in directions that intersect each other,
The 0.2% yield strength of the aluminum-based wire is 50 to 120 MPa,
When viewed in a longitudinal cross-section of the stranded conductor including the virtual center line of the central conductor wire, the aluminum-based strands located in the plurality of layers have a longitudinal dimension with respect to a radial dimension of the stranded conductor. Having a unit cross section with an average aspect ratio in the range of 4.2 to 13.0,
When viewed in the longitudinal section of the stranded conductor, two imaginary intermediate lines connecting positions corresponding to 50% of the radius of the stranded conductor are used as boundary lines, and the longitudinal section is defined by the two imaginary lines. When dividing into an inner layer side area of the stranded conductor partitioned by the intermediate line and an outer layer side area of the stranded conductor partitioned by each of the two virtual intermediate lines and the outer peripheral surface of the stranded conductor, The average value of the aspect ratios of the unit cross-sectional portions of the aluminum-based wires located in the inner layer side region is larger than the average value of the aspect ratios of the unit cross-sectional portions of the aluminum-based wires located in the outer layer side region. Stranded conductor. Among the plurality of aluminum-based strands forming the plurality of layers, the aluminum-based strands are located in two layers adjacent to each other in the radial direction of the stranded conductor when viewed in a cross section in the longitudinal direction of the stranded conductor. The positional relationship is such that two or more second unit cross-sectional portions of the aluminum-based wire positioned radially outward overlap one first unit cross-sectional portion of the aluminum-based wire positioned radially inward. and, of the two or more second unit cross sections, the longitudinal center position of the second unit cross section having the largest longitudinal overlap ratio with the first unit cross section is the first unit cross section. 2. The stranded conductor according to claim 1 , which is within a dimension range corresponding to 35% of the longitudinal dimension of said first unit cross section from the longitudinal center position of said portion. The stranded conductor has an arithmetic mean height (Sa) of 0.4 μm or more on the surface portion of the outermost aluminum-based strand located in the outermost layer, which forms the outer peripheral surface of the crimped portion to which the connection member is crimped. 3. The stranded conductor according to claim 1, having a roughened area of 500 [mu]m or less. 4. The outermost layer aluminum-based wire is a round wire or a flat wire, and the ratio of the maximum wire diameter to the minimum wire diameter of the crimped portion is 1.1 or more and 2.0 or less on average. A stranded conductor as described in . When a load is applied to the stranded wire conductor to a cylindrical winding jig, the stranded wire is wound and then unloaded, the load required to give the stranded wire a bending habit with a curvature radius of 110 mm is the stranded wire The stranded conductor according to any one of claims 1 to 4 , wherein the cross-sectional area of the conductor is 0.025α[N] or less when α[mm ² ]. A stranded conductor according to any one of claims 1 to 5 ;
and an insulating coating formed on the outer peripheral surface of the stranded conductor. A covered electric wire according to claim 6 and a connection member crimped and fixed to the covered electric wire,
A covered wire with a connection member, wherein a standard deviation σ of resistance values between the aluminum-based wire and the connection member is 25% or less of an average of the resistance values.

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