JPH11289650A - Rubber molded part of power cable end - Google Patents

Abstract

PROBLEM TO BE SOLVED: To bolster an electrically weak point of a rubber molded part for use in a power cable, without increasing the thickness of the overall rubber molded part. SOLUTION: This rubber molded part is for power cable ends comprising a body 1 formed of insulating rubber and an electric field relaxing layer 3 which is placed on the inner circumference of the body 1. When the rubber molded part is attached to a cable end, the portion of the insulating rubber located in a position corresponding to the end of the cable shielding layer of the rubber molded part is made locally thick to form a tapered portion 4. Thus only the electrically weak point is thickened and thereby bolstered, and furthermore the body except for the tapered portion remains thin, therefore cable inserting operation is not interfered with.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber molded part used for forming a terminal portion of a rubber / plastic power cable such as a CV cable.

[0002]

2. Description of the Related Art FIG. 7 of Japanese Patent Application No. 8-37522 discloses a rubber molded part used at an end of a power cable. This is a cylindrical component that fits into the stripped cable end. The metal terminal is integrated with the end of the main body made of insulating rubber, and has a semiconductive electric field relaxation layer on the inner periphery of the main body. In such a rubber molded part, the position corresponding to the end of the shield layer of the cable tends to be an electrical weak point, and dielectric breakdown may proceed from this part.

[0003]

As a countermeasure, it is conceivable to increase the wall thickness of the entire body to reinforce insulation. However, in that case, it becomes difficult to attach the rubber molded part to the cable with the increase in thickness, and the workability of forming the terminal portion is poor.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and provides a rubber molded part capable of reinforcing an electric weak point without impairing the mountability to a cable. In the rubber molded part of the power cable terminal part having the relaxation layer, when the rubber molded part is attached to the end of the cable, the thickness of the rubber molded part at the position corresponding to the end of the cable shielding layer is locally thickened. I did it.

Here, the present invention includes not only a terminal treatment material but also a rubber molded part such as a linear connection material. In addition, the end of the cable shielding layer includes the end (cable tip side) of the semiconductive tape wound around the outer periphery of the shielding layer when forming the terminal portion. In the case of a general terminal treatment material, the locally thickened material may be at least one of the body of the insulating rubber and the semiconductive electric field relaxation layer. When the main body of the insulating rubber is locally formed to be thick, it is preferable that the upper end side (metal terminal side) of the rubber molded component is formed to be thin and the lower end side is formed to be tapered. In particular, in the case of an outdoor rubber molded part, by forming a locally thick part in a tapered shape, the cut of rainwater or the like is improved, which is effective in suppressing tracking. In addition, since a locally thick portion is provided with a strong tightening force, the end of the cable shielding layer is strongly pressed to suppress generation of minute voids, thereby suppressing generation of electric discharge.

Further, it is preferable that at least one protrusion is formed at an end of a contact surface of the rubber molded component with the power cable insulator. These projections form a gap between the cable insulator and the lubricant, so that the lubricant can easily enter between the rubber mold component and the insulator, and the mountability of the rubber mold component can be further improved.

[0007]

Embodiments of the present invention will be described below. 1 is a partial cross-sectional view showing a rubber molded part for indoor use of the present invention, FIG. 2 is a partial cross-sectional view showing a state where the part is mounted on a cable end, and FIG. 3 is a cross-sectional view of the rubber molded part shown in FIG. .

The rubber molded part is a cylindrical main body 1.
And a metal terminal 2 integrated with the tip of the main body 1,
An electric field relaxation layer 3 is integrally formed on the inner periphery of the intermediate portion of the main body (FIG. 1). The main body 1 was made of insulating rubber, and the electric field relaxation layer 3 was made of semiconductive rubber. In this main body, the position (tapered portion 4) corresponding to the end of the cable shielding layer when attached to the cable is locally thickened. The locally thick portion was tapered so that the upper end (the metal terminal side) was thinner and the lower end side was thick. In this example, the thickness of the main body other than the tapered portion is 2.5 mm, the thickness of the thickest portion of the tapered portion is about 5 mm, and the length of the tapered portion is 10 mm. And

On the other hand, the end of the cable to be inserted into the rubber molded part is provided with a conductor, an inner semiconductive layer, an insulator, an outer semiconductive layer, a shielding layer, and a sheath in order from the inner periphery. When mounting a rubber molded part, the end of the cable is stripped off. Then, a semiconductive tape is wound from the shielding layer to the insulator.

As shown in FIG. 2, when the rubber molded part is attached to the end of the cable, the tapered portion 4 corresponds to the end of the semiconductive tape 5 wound around the cable shielding layer. Therefore, only the electrical weak points are thickened and reinforced, and the thickness of the main body other than the tapered part can be reduced,
It does not impair the cable insertability.

Another configuration of the rubber molded part will be described (FIG. 1). An annular protrusion 6 was formed at a predetermined position from the opening on the inner peripheral surface of the rubber molded part. The position of the annular projection 6 indicates a position where the rubber molded part is folded back when the cable is mounted on the cable, and corresponds to the position of the end of the cable sheath when the cable is just inserted.

Further, an arrow 7 is formed on the inner peripheral surface of the rubber mold part, pointing to the annular projection 6 from the opening side. A total of four arrows 7 are provided at positions shifted by 90 ° on the inner peripheral surface. In the case of only the annular projection 6,
When the rubber molded part is folded at the position of the annular projection 6, the position of the annular projection 6 can be confirmed only from the opening side in the folded state. However, even if the turning position is shifted from the position of the annular projection 6 by providing the arrow 7, the position of the annular projection can be easily determined by checking the arrow 7 from the side of the rubber molded component.

Further, FIG. 3 shows a cross-sectional structure of each part in the rubber molded part. X- in FIG.
FIG. 3A shows an X section, FIG. 3B shows a YY section, and FIG.
FIG. 3C shows the -Z cross section.

(A) As shown in the figure, the upper part of the main body 1 is formed with four ribs 8 along the axial direction, and the strength of the upper part of the main body is maintained, and the peripheral wall is formed thin so that it can be attached to the cable. It is configured so that it can be easily done. In addition, the rib 8 can easily determine if a twist occurs when the cable is attached to the cable.

As shown in FIG. 1B, the middle part of the main body is formed of an electric field relaxation layer 3 of semiconductive rubber on the inner peripheral side and a main body 1 of insulating rubber on the outer peripheral side. Also, as shown in FIG.
A plurality of hemispherical projections 9 were formed at the lower end of the electric field relaxation layer 3 (the end of the contact surface with the insulator). When attaching to a cable,
Due to the presence of the hemispherical projections 9, a gap is formed between the electric field relaxation layer 3 and the cable insulator so that the lubricant easily enters the upper end side of the main body. Therefore, the rubber molded part can be easily fitted to the cable end.
The shape of the projection is not particularly limited.

Further, the lower end of the main body 1 is made of insulating rubber as shown in FIG. 3 (C). It is desirable to form an annular protrusion (not shown) on the outer periphery of the lower end of the main body to indicate the position of a tightening band (not shown).

The mounting of the rubber molded part on the cable is performed as follows. First, the opening side of the rubber molded part is folded back with reference to the position of the annular projection 6. In this state, cover the end of the stripped cable with the annular projection 6
To the position where it comes into contact with the end of the sheath. If the folded position of the rubber molded part is displaced during this mounting, the folded position is adjusted again with reference to the annular projection 6 while looking at the arrow 7. When the annular projection 6 is fitted back to the position where the annular projection 6 comes into contact with the end of the sheath with the annular projection 6 folded as a reference, it means that the cable end has been inserted to the correct position in the rubber mold part. further,
As shown in FIG. 2, return the folded portion to the original position, cover it over the cable sheath 10, and tighten the tightening band around the lower end of the main body.
Attach 11 to configure the cable terminal. In FIG.
The conductor 12 is inserted into the metal terminal 2, and the ground wire 13 is drawn out below the terminal.

In the above description, an indoor rubber molded part has been described as an example. However, as shown in FIG. 4, an outdoor rubber in which a plurality of circumferential folds 20 are provided on the outer periphery of the main body 1 to increase the creepage distance. The present invention can be applied to a molded part.

[0019]

As described above, according to the rubber molded part of the present invention, the portion corresponding to the end of the cable shielding layer, which is an electrical weak point, is locally thickened so that it can be attached to the cable. It can be electrically reinforced without impairing the properties. In addition, by forming at least one projection at an end of the contact surface of the rubber molded component with the power cable insulator, a gap is formed between the rubber molded component and the cable insulator, and the lubricant is formed between the rubber molded component and the insulator. And the cable can be easily attached to the cable, and the mountability to the cable can be further improved. Therefore, a more reliable cable terminal can be formed.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view showing an indoor rubber molded part of the present invention.

FIG. 2 is a partial cross-sectional view showing a state where the rubber molded part of FIG. 1 is mounted on a cable terminal.

3A is a sectional view taken along line XX of FIG. 1, and FIG.
FIG. 7C is a sectional view taken along the line Y, and FIG.

FIG. 4 is a partial sectional view showing a rubber molded part for outdoor use according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Main body 2 Metal terminal 3 Electric field relaxation layer 4 Tapered part 5 Semiconductive tape 6 Annular protrusion 7 Arrow 8 Rib 9 Hemispherical protrusion 10 Sheath 11 Tightening band 12 Conductor 13 Ground wire
20 folds

Claims (2)

[Claims] In a rubber molded part of a power cable terminal part having an electric field relaxation layer, when this rubber molded part is attached to an end of a cable, a thickness of the rubber molded part at a position corresponding to an end of a cable shielding layer in the rubber molded part. A rubber molded part characterized by having a locally thickened portion. 2. The rubber molded part according to claim 1, wherein at least one projection is formed at an end of a contact surface of the rubber molded part with the power cable insulator.