JP2001076551A - Shielded cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shielded cable, particularly a CAN shielded cable, satisfying the required characteristic impedance along the miniaturization trend of a device and a facility, and making a widely used insulation displacement terminal applicable. SOLUTION: This shielded cable is preferably used particularly for the CAN system of an automobile, and an insulation displacement terminal is applied at its end section. Two electric wires each formed with a first insulating cover 12 around a conductor 11 are arranged in parallel, the surrounding is covered with a second insulating cover 13, and the periphery is covered with a shielding layer 14 and an insulating sheath 15 to form this shielded cable, which has a two-layer insulating cover structure comprising the first insulating cover 12 and second insulating cover 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a shielded cable, and more particularly to a shielded cable suitable as a CAN cable for an automobile.

[0002]

2. Description of the Related Art In recent years, a CAN system has been proposed for automobiles, and a shielded cable used in the system is required to have a characteristic impedance of 120Ω (defined in ISO-11898). FIG. 2 is a sectional view of a conventional shielded cable for CAN. As shown in the drawing, this shielded cable is composed of two parallel electric wires each having an insulating coating 22 formed around a conductive wire 21 and a shield layer 2 surrounding the electric wire.
3 and the periphery thereof is further covered with an insulating sheath 24.

[0003] On the other hand, at the present time, in the pressure welding connection of shielded cables for automobiles, from the viewpoint of miniaturization of equipment and facilities,
As the crimping terminal, a so-called 025 crimping terminal is used,
Very often, a 2 mm pitch connector is used as a connector. In this case, the diameter of the wire is limited to a maximum of 0.9 mm.

Considering the application of the 025 press-connecting terminal to a shielded cable having a structure as shown in FIG. 2, in a general case, the conductor 21 has a diameter of 0.3 mm.
An electric soft copper stranded wire of 5 mm is used, and foamed polyethylene having a dielectric constant of 1.7 is used as the insulating coating 22.
The characteristic impedance of the shielded cable is
And the dimensions of the conductive wire 21, the shield layer 23, and the insulating sheath 24. While properly maintaining the shield characteristics of the shield layer 23 and the insulation characteristics of the insulating sheath 24, the characteristic impedance of the shielded cable 120Ω
In order to obtain the thickness, the thickness of the insulating coating 22 must be 0.4 mm. Then, the outer diameter of the electric wire becomes 1.3 mm, which exceeds the limit of 0.9 mm. If the thickness of the insulating coating 22 is reduced, the required characteristic impedance cannot be obtained.

[0005] As described above, the conventional and frequently used specifications do not allow the application of the 025 press-connecting terminal to the CAN cable, which is against the flow of miniaturization of equipment and facilities. Therefore, it is desired to take some measures. Was.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, and satisfies the required characteristic impedance in accordance with the trend of miniaturization of equipment and facilities. Cable to which the terminal for
In particular, it is an object to provide a shielded cable for CAN.

[0007]

According to the present invention, in order to solve the above-mentioned problems, a plurality of electric wires provided with a first insulating coating around a conductor are arranged in parallel, and a second electric wire is provided around these electric wires. There is provided a shielded cable characterized in that the shielded cable is configured to be covered with an insulating coating, and further to be surrounded by a shielding layer and an insulating sheath in that order. Further, according to the present invention, there is provided a shielded cable having the above configuration, which is a shielded cable for an automobile. Further, according to the present invention, there is provided a shielded cable according to the above configuration, wherein the shielded cable is a cable for CAN and the characteristic impedance of the cable is approximately 120Ω. Further, according to the present invention, there is provided a shielded cable having the above-described configuration, wherein a press-connecting terminal is applied to an end of the cable.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to examples. FIG. 1 shows the structure of a shielded cable according to the present invention. This shielded cable is C
Particularly preferably used in AN systems,
This is a type in which a press contact terminal is applied to the end. As shown in the figure, this shielded cable is composed of two electric wires each having a first insulating coating 12 formed around a conducting wire 11, covered with a second insulating coating 13, and further shielded therearound. It is configured to be covered with the layer 14 and the insulating sheath 15. That is, the insulating coating has a two-layer structure of the first insulating coating 12 and the second insulating coating 13.

In the present invention, as the conducting wire 11, a conducting wire having an electric resistance of 70 mΩ / m or less, for example, a twisted copper wire for electric use is used, and its diameter is usually about 0.5 mm, but is not limited thereto. As the first insulating coating 12, one having a dielectric constant of 1.6 to 2.3 is preferably used,
Specifically, foamed polyethylene or the like is used. For example,
When foamed polyethylene having a dielectric constant of 1.7 is used, the thickness is about 0.2 mm. As described above, the second insulating coating 13 preferably has a dielectric constant of 1.6 to 2.3, and specifically, foamed polyethylene or the like is used. The materials of the first insulating coating 12 and the second insulating coating 13 may be the same or different. A release layer may be provided between the first insulating coating 12 and the second insulating coating 13 to facilitate the separation. In this case, the release layer can be formed using, for example, a silicon-based release material. As the shield layer 14, a material having a shielding effect is used. Specifically, Sn-plated copper foil PET tape, Sn-plated copper foil /
PET tape, aluminum PET tape, or the like can be used, and its thickness is about 0.1 to 0.3 mm. As the insulating sheath 15, a material having insulating properties, oil resistance, and chemical resistance is used. Specifically, an insulating material such as PVC or a polyolefin resin can be used.
It is about 0.3 mm.

In the shielded cable of the present invention, for example, a round single-core electric wire (core) is made by ordinary electric wire extrusion, two of these electric wires are arranged, and further extruded into an oval shape. It can be manufactured by coating the shield layer and the insulating sheath, but is not limited to this method.

Here, an example to which the 025 pressure contact terminal can be applied will be described. Soft copper stranded wire for electrical use (outer diameter 0.5 mm) as the conductive wire 11, foamed polyethylene (dielectric constant 1.7, thickness 0.2 mm) as the first insulating coating 12, foamed polyethylene (dielectric constant) as the second insulating coating 13 Rate 1.7, thickness 0.2 mm), Sn-plated copper foil P as shield layer 14
By using an ET tape (0.1 mm thick) and PVC (0.5 mm thick) as the insulating sheath 15, the structure shown in FIG. In the crimping connection operation, only the first insulating coating of the two insulating coatings is used near the exposed portion of the conductive wire at the connection end.

[0012]

According to the present invention, since the above-mentioned structure is employed, it is possible to easily cope with the current press-connecting terminal and to reduce the size of wiring and equipment. Further, the shielded cable of the present invention is particularly suitable as a shielded cable for CAN in an automobile.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a structure of a shielded cable according to the present invention.

FIG. 2 is a sectional view showing the structure of a conventional shielded cable for CAN.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Conductor 12 First insulating coating 13 Second insulating coating 14 Shield layer 15 Insulating sheath

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masanobu Yoshimura 1-7-10 Kikuzumi, Minami-ku, Nagoya City, Aichi Prefecture Inside Harness Research Institute Co., Ltd. No. 7-10 Harness Research Institute, Inc. (72) Inventor Shizuya Kawabe 1-10 Kikuzumi, Minami-ku, Nagoya-shi, Aichi F-term in Harness Research Institute, Inc. 5G311 CA05 CB02 CC01 CD05 CE01 CF02 CF04 5G319 EA01 EA05 EB04 EB06 EC04 ED01

Claims (4)

[Claims] 1. A plurality of electric wires having a first insulating coating provided around a conducting wire, a plurality of electric wires are arranged in parallel, the surroundings of these electric wires are coated with a second insulating coating, and the surroundings are further covered with a shield layer and an insulating sheath. A shielded cable characterized by being sequentially coated. 2. The shielded cable according to claim 1, which is a shielded cable for an automobile. 3. The shielded cable according to claim 1, wherein the cable is a CAN (Controller Area Network) cable, and the characteristic impedance of the cable is approximately 120Ω. 4. The shielded cable according to claim 1, wherein a pressure contact terminal is applied to an end of the cable.