Patent Grant
7409816
This invention relates to a concentric strand excellent in flexibility, particularly to a concentric stranded conductor for electrical transmission which is excellent in flexibility and is used in automobiles and the like.
Copper has been the main material used for concentric stranded conductors (rope lay concentric conductors) for electrical transmission used in automobiles and the like. In recent years, automobiles and the like are required to be lightweight in view of considerations such as energy-saving and, environmental preservation. Therefore, weight reduction of the concentric stranded conductor for electrical transmission is desirable. As a method for reducing weight, it has been proposed to use aluminum, which has small specific gravity, in place of copper.
An example is a concentric stranded conductor for electrical transmission that is excellent in bending resistance and vibration resistance and is resistant to breakage by friction and wearing at the time of bending and vibration (for example, see JP-A-2003-303515 (“JP-A” means unexamined published Japanese patent application)).
a) is a partially cut-away perspective view showing the concentric stranded conductor for electrical transmission described in JP-A-2003-303515.
Automobiles equipped with large capacity batteries, such as electric cars and hybrid cars, have appeared in recent years. Aluminum concentric stranded wires are also used in such vehicles as conductors for transmission of electricity from the battery. Since the amount of electricity conducted is large in these automobiles, a concentric stranded wire having a larger diameter than conventional ones is used. However, this raises the concern that the larger diameter may make attachment of the concentric stranded wire to the body of the automobile difficult. In addition, wires are required to be installed in a limited space. A concentric stranded conductor with better flexibility is therefore desired.
The object of the invention is to solve the above-mentioned problems and to provide a concentric stranded conductor excellent in flexibility.
In order to solve the above-mentioned problems, the invention in a first aspect provides a concentric stranded conductor having a concentric strand comprising a plurality of strands twisted together, in which each of the strands comprises a plurality of single wires twisted together; wherein the concentric stranded conductor has a central core strand (5) and a first concentric strand layer (11) which comprises a plurality of first-layer strands (9) twisted together around the central core strand (5); wherein a twist pitch of the central core strand (5) is from 8 to 70 times a distance between diametrically opposed outer wires of the central core strand (5), a twist pitch of the first concentric strand layer (11) is from 8 to 30 times a distance between diametrically opposed strands of the first concentric strand layer (11), |α−(β+γ)| is 15 degrees or less, where α is a twist angle of the central core strand (5), β is a twist angle of the first-layer strands (9) and γ is a twist angle of the first concentric strand layer (11), and each of the single wires is made of aluminum or an aluminum alloy, each having elongation of 2% or more.
The invention in a second aspect provides a concentric stranded conductor according to the first embodiment, wherein the central core strand (5), the first-layer strands (9), and the first concentric strand layer (11) are all twisted in the same direction.
The invention in a third aspect provides a method for producing a concentric stranded conductor (1) comprising the steps of: twisting, around a central core strand (5), a first concentric strand layer (11) in the same direction as the twist direction of the central core strand (5), the first concentric strand layer (11) comprising first-layer strands (9) each twisted in the same direction as the twist direction of the central core strand (5); and twisting, around the first concentric strand layer (11), a second concentric strand layer (17) in the same direction as the twist direction of the central core strand (5), the second concentric strand layer (17) comprising second-layer strands (15) each twisted in the same direction as the twist direction of the central core strand (5); wherein the conductor uses single wires of aluminum or an aluminum alloy each having elongation of 2% or more; wherein a twist pitch of the central core strand (5) is from 30 to 70 times a distance between diametrically opposed outer wires of the central core strand (5); wherein a twist pitch of the second concentric strand layer (17) is from 10 to 30 times a distance between diametrically opposed strands of the second concentric strand layer (17); and wherein the twist pitch of the first concentric strand layer (11) is the same as or larger than the twist pitch of the second concentric strand layer (17) and a difference between the twist pitches is 20 times or lower.
The invention in a fourth aspect provides a method for producing a concentric stranded conductor, wherein, in the method for producing a concentric stranded conductor according to the third embodiment, multiple layers of concentric strands, each of which comprises strands twisted together in the same direction as the twist direction of the central core strand (5), are twisted in the same direction as the twist direction of the central core strand (5) around the second concentric strand layer (17).
The invention in a fifth aspect provides a concentric stranded conductor having a second concentric strand layer (17) comprising a plurality of second-layer strands (15) twisted together around the concentric stranded conductor according to the first or second embodiment, wherein |α−(δ+ε)| is 15 degrees or less, where α is the twist angle of the central core strand (5), δ is a twist angle of the second-layer strands (15) and ε is a twist angle of the second concentric strand layer (17); wherein |(β+γ)−(δ+ε)| is 15 degrees or less, where β is the twist angle of the first-layer strands (9), γ is the twist angle of the first concentric strand layer (11), δ is the twist angle of the second-layer strands (15) and ε is the twist angle of the second concentric strand layer (17); and wherein a twist pitch of the second concentric strand layer (17) is from 8 to 30 times a distance between diametrically opposed strands of the second concentric strand layer (17).
The invention in a sixth aspect provides a concentric stranded conductor wherein, in the concentric stranded conductor according to the fifth embodiment, the central core strand (5), the first-layer strands (9), the first concentric strand layer (11), the second-layer strands (15), and the second concentric strand layer (17) are all twisted in the same direction.
The “distance between diametrically opposed strands” as termed with respect to the present invention means a diameter obtained by subtracting an outer diameter of one single wire from an outer diameter of a stranded wire.
A proportion of surface contact between single wires is enhanced in the invention. Accordingly, since concentrated contact portions between the layers as in the prior art are dispersed in the invention, local nicking decreases and flexibility is improved due to good slidability between single wires. Since the entire single wires are aligned in the same twist direction by twisting all of strands and concentric strands in the concentric stranded conductor, the single wires are brought into surface contact and flexibility is further improved.
Other and further features and advantages of the invention will appear more fully from the following description, appropriately referring to the accompanying drawings.
a) is a schematic partial perspective view of a preferred embodiment of this invention and
a) is a schematic partial perspective view of a prior art conductor and
Preferred embodiments of the invention will be described below.
The concentric stranded conductor (1) of the invention comprises a concentric strand formed by twisting sets of single wires into strands and then twisting together a plurality of such strands. Particularly, it is preferable that the concentric stranded conductor (1) comprise multiple layers wherein the twist directions of the central core strand (5), the first-layer strands (9), the first concentric strand layer (11), the second-layer strands (15), and the second concentric strand layer (17) are all the same, i.e., the twist directions of the strands of each layer (“twist direction of strand” means the twist direction of the single wires forming the strand) and the twist directions of the concentric strands of each layer (“twist direction of concentric strand” means the twist direction of the strands forming the concentric strand) are all the same.
a) is a partially cut-away perspective view showing the concentric stranded conductor (1).
b) is a schematic cross section of the concentric stranded conductor (1). The arrows in
Then, twelve of second-layer strands (15) each formed by twisting together single wires (13) counterclockwise are twisted counterclockwise around the first concentric strand layer (11) to form the second concentric strand layer (17). The second concentric strand layer (17) is coated with an insulator coating (21) so as to contact the surface closely.
For improving the flexibility of the conductor, the twist direction of the central core strand (5) is preferably the same as the twist direction of the first concentric strand layer (11) provided around the central core strand (5).
The first concentric strand layer (11) is preferably twisted in the same twist direction as the first-layer strands (9). Twisting the first concentric strand layer (11) and the first-layer strands (9) in the same direction is preferable because it brings the single wires (7) in the first-layer strands (9) into surface contact with one another and deforms the cross sectional shape of the strands of the first concentric strand layer (11). In other words, the twisting deforms the cross-sectional shape of the first-layer strands (9) into a trapezoid-like shape (i.e., a shape obtained by subtracting a sector having an angle of 180° or less from a larger similar sector), thus bringing the adjoining first-layer strands (9) into close contact and reducing gaps.
The second concentric strand layer (17) is preferably twisted in the same direction as the second-layer strands (15). Twisting the second concentric strand layer (17) and the second-layer strands (15) in the same twist direction is preferable because it brings the single wires (13) of the second-layer strands (15) into surface contact with one another and deforms the cross-sectional shape of the second-layer strands (15).
As shown in
In order to improve flexibility of the conductor, the twist pitch of the central core strand (5) is defined as from 8 to 70 times the distance between diametrically opposed outer wires of the central core strand (5), and more preferably from 10 to 30 times said distance.
In order to improve flexibility of the conductor, the twist pitch of the first concentric strand layer (11) is defined as from 8 to 30 times the distance between diametrically opposed strands of the first concentric strand layer (11), and more preferably from 10 to 20 times said distance.
In order to improve flexibility of the conductor, the twist pitch of the second concentric strand layer (17) is preferably 8 to 30 times the distance between diametrically opposed strands of the second concentric strand layer (17). The twist pitch is more preferably from 10 to 20 times. The twist pitch (see
In order to improve flexibility, |α−(β+γ)| is defined as from 15 degrees or less to 0 degree or more, more preferably from 10 degrees or less to 0 degree or more, where α is the twist angle of the central core strand (5), β is the twist angle of the first-layer strands (9) and γ is the twist angle of the first concentric strand layer (11). In order to improve flexibility, it is also preferable for |α−(δ+ε)| to be from 15 degrees or less to 0 degree or more, more preferably from 10 degrees or less to 0 degree or more, where α is the twist angle of the central core strand (5), δ is the twist angle of the second-layer strands (15) and ε is the twist angle of the second concentric strand layer (17). In addition, for improving flexibility, |(β+γ)−(δ+ε)| is preferably from 15 degrees or less to 0 degree or more, more preferably from 10 degrees or less to 0 degree or more, where β is the twist angle of the first-layer strands (9), γ is the twist angle of the first concentric strand layer (11), δ is the twist angle of the second-layer strands (15) and ε is the twist angle of the second concentric strand layer (17). The twist angle is an angle in the longitudinal direction of strands or concentric strands.
By forming a concentric stranded conductor (1) as shown in
In the following, the invention is described in more detail, but only for purposes of illustration and not for limitation.
In the concentric stranded conductor (1), for example, the central core strand (5) formed by twisting thirteen aluminum single wires (3) with a diameter of 0.32 mm together in the counterclockwise direction is placed at the center, and six first-layer strands (9) each formed by twisting thirteen aluminum single wires (7) with a diameter of 0.32 mm together in the counterclockwise direction are twisted together in the counterclockwise direction to form the first concentric strand layer (11).
The twist direction of the first concentric strand layer (11) is preferably the same as the twist direction of the first-layer strands (9). Twisting in the same twist direction is preferable since the single wires (7) of the first-layer strands (9) are brought into surface contact with one another, causing the first-layer strands (9) to be twisted so that the cross-sectional shape of each strand is deformed. As shown in
The central core strand (5) is preferably stranded in the same twist direction for improving flexibility. The stranding in the same twist direction may be conducted using a bunch strander. The first concentric strand layer (11) and the second concentric strand layer (17) may be twisted using a planetary strander (with back-twist functionality) or rigid strander (without back-twist functionality).
A second concentric strand layer (17) is preferably disposed around the first concentric strand layer (11). Such a second concentric strand layer (17) is formed by stranding clockwise twelve second-layer strands (15) each formed of thirteen single wires (13) twisted together counterclockwise.
Twisting the second concentric strand layer (17) and the second-layer strands (15) in the same twist direction is preferable, since the single wires (13) of the second-layer strands (15) are brought into surface contact with one another, and the second-layer strands (15) are twisted so that the cross sectional shape of each strand is deformed.
Compared with conventional structures, concentric strands having strands with a deformed cross sectional shape can achieve smaller outer diameter and also reduce the outer diameter of the coating. Further, since the surface roughness is reduced, the ratio of the thickness of a thick part to the thickness of a thin part of the insulator coating (21) (roughness of the inner surface of the insulator coating) can be reduced, and this enables the amount of the coating material to be reduced.
According to the invention, because the roughness of the outer circumference of the concentric stranded conductor (1) is reduced, the insulator coating (21) scarcely penetrates into the gaps around the second concentric strand layer (17). Accordingly, concentration of adhesive force can be relaxed since the adhesive force between the insulator coating (21) and the concentric stranded conductor (1) is shared by the whole concentric stranded conductor (1). Consequently, the conductor becomes easy to bend (good flexibility) and slidability is improved, resulting in improvement of bending resistance and wear resistance.
According to the invention, the single wires (7) and single wires (13) are brought into surface contact with one another. Consequently, local nicking is reduced since concentrated contact parts among the layers are dispersed, resulting in improvement of bendability and slidability as well as improvement of bending resistance and wear resistance.
According to the invention, since crossover between single wires is reduced inside a terminal, nicking of single wires is reduced and therefore strength deterioration of the electrical wire at the time of solderless connection or weld connection is reduced.
The invention is by no means restricted to the embodiments set out herein, and may be implemented in various embodiments falling within the gist of the invention. For example, while the twist direction is counterclockwise in the above-mentioned embodiments, the twist direction may be clockwise.
The conductor of the invention is preferably formed by coating the concentric stranded conductor (1), which comprises single wires (3), (7), and (13) of aluminum or aluminum alloy, with the insulator coating (21). The single wires (3), (7), and (13) preferably have elongation of 2% or more because this improves flexibility. The elongation is more preferably 5% or more and is further preferably 15% or more. The aluminum or aluminum alloy used can be of any type insofar as it can be processed into the single wires (3), (7), and (13), and the aluminum alloy is not particularly restricted by its alloy components.
In the following, preferable embodiments when preparing the concentric stranded conductors of the invention as concentric stranded conductors for electrical transmission in automobiles and the like will be described.
While the diameter of the single wire is not particularly restricted, it is usually from 0.16 mm to 1.0 mm, preferably about 0.3 mm. While the number of the single wires constituting the central core strand is not particularly restricted, it is usually from 7 to 80 single wires, preferably from 10 to 30 single wires. While the number of the single wires constituting the strands in the n-th layer (n is an integer of 1 or more) is not particularly restricted, it is usually from 7 to 80 single wires, preferably from 10 to 30 single wires. While the number of the strands constituting the n-th layer concentric strand (n is an integer of 1 or more) is not particularly restricted, it is usually from 6 to 80 strands, preferably from 7 to 80 strands, and more preferably from 10 to 30 strands. While the number of concentric strand layers is not particularly restricted, it is usually from 1 to 3 layers, more preferably from 2 to 3 layers.
As the insulator coating, any of those generally used for conventional concentric stranded conductors may be used, and it is preferably a polyethylene resin or a Noryl (registered trademark) resin. In the following, the present invention will be described in more detail based on examples, but the invention is not meant to be limited by these.
As the examples of the invention, concentric stranded conductors were produced by the following procedures, using a strander. Firstly, a central core strand (5) formed by twisting thirteen aluminum single wires (3) with a diameter of 0.32 mm together in the counterclockwise direction was placed at the center, and six first-layer strands (9) each formed by twisting thirteen aluminum single wires (7) with a diameter of 0.32 mm together in the counterclockwise direction were twisted counterclockwise to form a first concentric strand layer (11). In Examples 16 to 24, these were used as concentric stranded conductors, without further modification.
In Examples 1 to 15, the second-layer strands (15) were formed by twisting thirteen aluminum single wires (13) together, and the second concentric strand layer (17) was formed by twisting twelve second-layer strands (15) counterclockwise around the first concentric strand layer (11). For the purpose of comparison, Comparative Examples 1 to 22 were prepared with appropriate changes in the kind of the strand, the twist angle, and the twist pitch.
The prepared concentric stranded conductors (1) were evaluated using a flexibility tester (51) as shown in
As is apparent from Tables 1 and 2, the examples according to the invention exhibited small amount of displacement and were excellent in flexibility.
On the contrary, in Comparative Example 1, concentric stranding was impossible since |α−(β+γ)| exceeded 15 degrees, where α is the twist angle of the central core strand (5), β is the twist angle of the second-layer strands (15) and γ is the twist angle of the second concentric strand layer (17).
Comparative Example 2 exhibited a large amount of displacement, since the twist pitch of the central core strand (5) exceeded 70 times the distance between diametrically opposed outer wires of the central core strand (5).
Comparative Example 3 exhibited a large amount of displacement, since the twist pitch of the first concentric strand layer (11) exceeded 30 times the distance between diametrically opposed strands of the first concentric strand layer (11).
Comparative Example 4 exhibited a large amount of displacement, since the twist pitch of the first concentric strand layer (11) exceeded 30 times the distance between diametrically opposed strands of the first concentric strand layer (11) and the twist pitch of the second concentric strand exceeded 30 times the distance between diametrically opposed strands of the second concentric strand.
In Comparative Example 5, concentric stranding was impossible, since |α−(δ+ε)| exceeded 15 degrees, where α is the twist angle of the central core strand (5), δ is the twist angle of the second-layer strands (15) and ε is the twist angle of the second concentric strand layer (17).
In Comparative Example 6, concentric stranding was impossible, since |α−(β+γ)| exceeded 15 degrees, where α is the twist angle of the central core strand (5), β is the twist angle of the first-layer strands (9) and γ is the twist angle of the first concentric strand layer (11).
Comparative Example 7 exhibited a large amount of displacement, since the elongation of the strands was less than 2% and |α−(δ+ε)| exceeded 15 degrees, where α is the twist angle of the central core strand (5), δ is the twist angle of the second-layer strands (15) and ε is the twist angle of the second concentric strand layer (17).
Comparative Example 8 exhibited a large amount of displacement, since |α−(β+γ)| exceeded 15 degrees, where α is the twist angle of the central core strand (5), β is the twist angle of the first-layer strands (9) and γ is the twist angle of the first concentric strand layer (11).
Comparative Example 9 exhibited a large amount of displacement, since |α−(β+γ)| exceeded 15 degrees, where α is the twist angle of the central core strand (5), β is the twist angle of the first-layer strands (9) and γ is the twist angle of the first concentric strand layer (11).
Comparative Example 10 exhibited a large amount of displacement, since |α−(δ+ε)| exceeded 15 degrees, where α is the twist angle of the central core strand (5), δ is the twist angle of the second-layer strands (15) and ε is the twist angle of the second concentric strand layer (17).
Comparative Example 11 exhibited a large amount of displacement, since |α−(δ+ε)| exceeded 15 degrees, where α is the twist angle of the central core strand (5), δ is the twist angle of the second-layer strands (15) and ε is the twist angle of the second concentric strand layer (17), and since |(β+γ)−(δ+ε)| exceeded 15 degrees, where β is the twist angle of the first-layer strands (9), γ is the twist angle of the first concentric strand layer (11), δ is the twist angle of the second-layer strands (15) and ε is the twist angle of the second concentric strand layer (17).
Comparative Example 12 exhibited a large amount of displacement, since the elongation of the single wires was less than 2%.
Comparative Example 13 exhibited a large amount of displacement, since the elongation of the single wires was less than 2%.
In Comparative Example 14, concentric stranding was impossible, since the twist pitch of the central core strand (5) was less than 8 times the distance between diametrically opposed outer wires of the central core strand (5).
Comparative Example 15 exhibited a large amount of displacement, since the twist pitch of the first concentric strand layer (11) was less than 8 times the distance between diametrically opposed strands of the first concentric strand layer (11).
Comparative Example 16 exhibited a large amount of displacement, since the twist pitch of the second concentric strand was less than 8 times the distance between diametrically opposed strands of the second concentric strand, and since |α−(δ+ε)| exceeded 15 degrees, where α is the twist angle of the central core strand (5), δ is the twist angle of the second-layer strands (15) and ε is the twist angle of the second concentric strand layer (17).
Comparative Example 17 exhibited a large amount of displacement, since the twist pitch of the second concentric strand exceeded 30 times the distance between diametrically opposed strands of the second concentric strand.
In Comparative Example 18, concentric stranding was impossible, since the twist pitch of the central core strand (5) exceeded 70 times the distance between diametrically opposed outer wires of the central core strand (5).
In Comparative Example 19, concentric stranding was impossible, since the twist pitch of the central core strand (5) was less than 8 times the distance between diametrically opposed outer wires of the central core strand (5).
Comparative Example 20 exhibited a large amount of displacement, since the twist pitch of the first concentric strand layer (11) was less than 8 times the distance between diametrically opposed strands of the first concentric strand layer (11).
In Comparative Example 21, concentric stranding was impossible, since the twist pitch of the first concentric strand layer (11) exceeded 30 times the distance between diametrically opposed strands of the twist pitch of the first concentric strand layer (11).
Comparative Example 22 exhibited a large amount of displacement, since |α−(β+γ)| exceeded 15 degrees, where α is the twist angle of the central core strand (5), β is the twist angle of the first-layer strands (9) and γ is the twist angle of the first concentric strand layer (11).
The invention provides a concentric stranded conductor excellent in flexibility that is suitable for use as a concentric stranded conductor for electrical transmission in automobiles and the like.
Having described our invention as related to the present embodiments, it is our intention that the invention not be limited by any of the details of the description, unless otherwise specified, but rather be construed broadly within its spirit and scope as set out in the accompanying claims.
This non-provisional application claims priority on Patent Application No. 2004-312575 filed in Japan on Oct. 27, 2004, and Patent Application No. 2005-288978 filed in Japan on Sep. 30, 2005, each of which is entirely herein incorporated by reference.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-312575 | Oct 2004 | JP | national |
| 2005-288978 | Sep 2005 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 3823542 | Pemberton | Jul 1974 | A |
| 5449861 | Fujino et al. | Sep 1995 | A |
| 5711143 | Munakata et al. | Jan 1998 | A |
| 6260343 | Pourladian | Jul 2001 | B1 |
| 6339920 | Yokoyama | Jan 2002 | B1 |
| Number | Date | Country |
|---|---|---|
| 10-321048 | Dec 1998 | JP |
| 11-120839 | Apr 1999 | JP |
| 2003-303515 | Oct 2003 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20070251204 A1 | Nov 2007 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP05/20158 | Oct 2005 | US |
| Child | 11790691 | US |
