JPH1040745A - Coaxial cable using litz wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coaxial cable that can be used for power distribution with one cable and free of generating a leakage flux. SOLUTION: A first conductor 10 is composed by bundling and stranding 19 litz wires 11, for example, and an outer circumference thereof is surrounded by a PVC-based interlayer insulation layer 18. A second conductor 20 is composed of 19 litz wires 21, and an outer circumference of the interlayer insulation layer 18 is disposed by surrounding it in a parallel spiral shape. In addition, one shield wire 22 is disposed in parallel to the litz wire 21, and the PVC-based outside insulation layer 28 and the external protection layer 29 are provided on the outside thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cable suitable for high frequency power distribution.

[0002]

2. Description of the Related Art As is well known, when a high-frequency current flows through an electric wire, an increase in resistance due to a skin effect becomes a problem. Therefore, a litz wire formed by twisting a plurality of insulated wires is used. Is used. As a high-frequency cable, for example, Japanese Unexamined Patent Application Publication No. 7-240120
As shown in FIG. 3, a coaxial cable described in Japanese Patent Application Laid-Open Publication No. H10-209, 1993, has a configuration in which a litz wire 1 is used as a core wire and a braided wire 3 for shielding is arranged around the outer periphery thereof via a rubber tube 2. . However, since the cable has one core wire, it is necessary to use two cables for power distribution, and there is a problem that it is bulky and difficult to handle.

In order to avoid this, as shown in FIG. 4, a structure in which the litz wire 1 has two cores and which is placed in a jacket tube 5 in parallel or twisted pair has been considered. However, this structure has a drawback that a high current is caused to generate a high-frequency magnetic field in the surroundings when the large current flows, because the function of canceling the magnetic field is not sufficient. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a coaxial cable which can be used alone for power distribution and does not generate a leakage magnetic flux.

[0004]

According to a first aspect of the present invention, there is provided a coaxial cable using a litz wire, wherein the first core wire is formed by twisting a plurality of litz wires obtained by bundling a plurality of insulated wires. An interlayer insulating layer provided on the outer periphery of the first core wire, and a plurality of litz wires, which are arranged concentrically with the first core wire so as to surround the outer circumference of the interlayer insulating layer, and have substantially the same conductor cutoff as the first core wire. It is characterized in that it is constituted by a second core wire having an area and an outer insulating layer provided on the outer periphery of the second core wire.

[0005] In the concentric cable using the litz wire according to the second aspect of the present invention, in the first aspect of the present invention, the litz wire constituting the second core wire is spirally arranged around the outer periphery of the interlayer insulating layer. It has features.

In the concentric cable using the litz wire according to the third aspect of the present invention, in the second aspect of the present invention, a signal shielded wire is further arranged around the interlayer insulating layer so as to form a spiral with the litz wire. However, it has features.

[0007]

According to the concentric cable of the first aspect, the first outer insulating layer has the first conductor having substantially the same conductor cross-sectional area.
Since the core wire and the second core wire are arranged, current can flow through each of the core wires, and a single cable can be used for power distribution. In addition, since each core wire is made of a litz wire, the resistance increase due to the skin effect when a high-frequency current flows is small, and the conduction loss is small. Moreover, even if the shield layer is not provided, the second core wire is arranged concentrically around the first core wire, so that the currents flowing through the respective core wires cancel each other out, so that the magnetic flux does not leak to the outside. , Can be prevented from becoming a noise source.

According to the coaxial cable of the second aspect, since the litz wire constituting the second core wire is helically arranged,
Even if the current distribution of each litz wire constituting the second core wire varies, the effect of reliably preventing leakage of magnetic flux can be obtained.

Further, according to the structure of the third aspect, it is possible to transmit a signal simultaneously with the electric power by the cable, and furthermore, while having a shielded signal wire, this forms a spiral with the litz wire constituting the second core wire. With such an arrangement, the effect that leakage of magnetic flux can be suppressed can be obtained.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

The cable of this embodiment is used, for example, to supply electric power for charging an electric vehicle to the electric vehicle side by an electromagnetic induction method, and a high-frequency current of several tens of kHz is supplied. As shown in FIG. 1, the structure is a two-core structure in which an interlayer insulating layer 18 made of PVC is provided around the outer periphery of the first core wire 10 and a second core wire 20 is arranged so as to surround the outer periphery. An outer insulating layer 28 also made of PVC and an outer protective layer 29 made of PVC located outside the two-core wire 20 are provided.

The first core wire 10 is formed by connecting the litz wire 11 to, for example, 1
It is configured by bundling and twisting nine wires. The litz wire 11 has a general structure in which a plurality of insulated wires 12 are bundled, and the type and number of the insulated wires 12 are determined in accordance with the required current carrying capacity and frequency. For example, a polyurethane insulated copper wire with a diameter of 0.18 mm
One is bundled and twisted.

On the other hand, the second core wire 20 is composed of 19 litz wires 21 similarly to the first core wire, and is arranged in a parallel spiral shape around the outer periphery of the interlayer insulating layer 18.
Each litz wire 21 is the same as the litz wire 11 constituting the first core wire 10, and accordingly, the second core wire 20 has the same conductor cross-sectional area as the first core wire 10.

In this embodiment, one two-core shielded wire 22 is spirally arranged in parallel with the litz wire 21 constituting the second core wire 20 so that information on charging of the electric vehicle can be transmitted. It has become. In addition, a binding tape 23 for bundling each litz wire 21 of the second core wire 20 and the two-core shielded electric wire 22 is spirally wound in a direction opposite to each litz wire 21. On the inner peripheral side of the outer insulating layer 28, a holding groove 28a is formed along the spiral arrangement of the litz wire 21 and the two-core shielded electric wire 22, and the litz wire 21 and the two-core shield are formed in the holding groove 28a. The electric wire 22 is fitted and held.

The coaxial cable of the present embodiment has the above-described configuration. Since the two core wires 10 and 20 have substantially the same conductor cross-sectional area, a high-frequency current can flow through the two core wires 10 and 20 as a pair. Only one cable is needed for power distribution. In addition, since each of the core wires 10 and 20 is composed of the litz wires 11 and 21 having a small conduction loss due to the skin effect, power can be transmitted efficiently even when a high-frequency current flows. Moreover, even if the shield layer is not provided, the second core wire 20 surrounds the first core wire 10 concentrically, so that the currents flowing through the two core wires 10 and 20 cancel each other to generate a magnetic flux to the outside. No leakage. For this reason, it is possible to reliably prevent a magnetic flux leaking from a cable during charging of an electric vehicle from inducing noise in surrounding electronic devices and communication devices such as a television and a radio, thereby causing malfunction and noise generation. it can. In addition, since the two core wires 10 and 20 are arranged concentrically, space efficiency is excellent, and the overall diameter is smaller than that of a two-core parallel electric wire or a twisted pair electric wire as shown in FIG. Can be. Incidentally, the same litz wires 11 and 12 as in the above-described embodiment.
When 1 is bundled by the same number to form a parallel two-core electric wire,
The outer diameter of the cable is about 20 mm, but in the concentric arrangement of the present embodiment, the outer diameter can be about 18 mm, and the reduction in diameter and weight can be achieved at the same current carrying capacity.

In the present embodiment, in particular, the second core wire 2
Since the litz wires 21 constituting 0 are spirally arranged, there is obtained an effect that leakage of magnetic flux can be reliably prevented even if the current distribution of each litz wire 21 varies. In addition, in the present embodiment, the two-core shielded electric wire 22 is arranged on the outer periphery of the interlayer insulating layer 18 together with the litz wire 21, so that information related to charging and the like can be transmitted and received between the charging power supply and the electric vehicle. it can. Moreover, such a shielded electric wire 2 for signals
2 is provided so as to form a spiral with the litz wire 21 constituting the second core wire 20, so that leakage of magnetic flux can be prevented.

<Other Embodiments> The present invention is not limited to the embodiments described above and illustrated in the drawings. For example, the following embodiments are also included in the technical scope of the present invention. In addition to the following, various changes can be made without departing from the scope of the invention.

In the above embodiment, the shielded signal wires 22 are arranged on the outer periphery of the interlayer insulating layer 18 side by side with the litz wires 21. However, this may be omitted if necessary. Also, even when providing shielded wires for signals,
This may be configured to be arranged side by side with the first core wire inside the interlayer insulating layer.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view of a cable showing one embodiment of the present invention.

FIG. 2 is a sectional view along line II-II of FIG.

FIG. 3 is a sectional view of a conventional cable.

FIG. 4 is a sectional view of a different type of cable.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... 1st core wire 11, 21 ... Litz wire 18 ... Interlayer insulating layer 20 ... 2nd core wire 22 ... 2 core shielded wire 28 ... Outer insulating layer 29 ... External protective layer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shoichi Kanekawa 1-114, Nishisuehiro-cho, Yokkaichi-shi, Mie Sumitomo Wiring Systems, Ltd. (72) Inventor Exit Yosei 4-33 Kitahama, Chuo-ku, Osaka-shi No. Within Sumitomo Electric Industries, Ltd. (72) Inventor Akashi Arisaka 4-33 Kitahama, Chuo-ku, Osaka City Inside Sumitomo Electric Industries, Ltd.

Claims (3)

[Claims] 1. A first core wire formed by twisting a plurality of litz wires obtained by bundling a plurality of insulated wires, an interlayer insulating layer provided on the outer periphery of the first core wire, and a plurality of litz wires. A second core wire arranged concentrically with the first core wire so as to surround the outer periphery of the interlayer insulating layer, and having a conductor cross-sectional area substantially the same as the first core wire, and provided on the outer periphery of the second core wire. Coaxial cable using litz wire consisting of an outer insulating layer. 2. A coaxial cable using a litz wire according to claim 1, wherein the litz wire constituting the second core wire is spirally arranged around the outer periphery of the interlayer insulating layer. 3. The coaxial cable using a litz wire according to claim 2, wherein a shielded signal wire is arranged around the interlayer insulating layer so as to form a spiral with the litz wire.