JP3351415B2 - Pre-molded rubber insulator for power cable connection - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pre-molded rubber insulator for connecting a plastic insulated power cable such as a CV cable.

[0002]

2. Description of the Related Art FIG. 3 is a longitudinal sectional view of a conventional pre-molded rubber insulator for a power cable connecting portion. In the drawing,
The pre-molded rubber insulator 4 has an outer semiconductive layer 1 provided on the outer periphery of the insulating layer 2 and an inner semiconductive layer 3 provided on the inner periphery of the insulating layer 2. As a method of manufacturing the pre-molded rubber insulator 4, the outer semiconductive layer 1 and the inner semiconductive layer 3 are manufactured in advance, and the outer semiconductive layer 1 and the inner semiconductive layer 3 are set in a mold. In addition, the outer semiconductive layer 1 and the inner semiconductive layer 3 are integrated with the insulating layer 2 by injecting an insulating material forming the insulating layer 2 from an injection hole 5 provided in the outer semiconductive layer 1. It is. The inner diameter of the pre-molded rubber insulator 4 is smaller than the outer diameter of the cable insulating core to be connected.

Here, when manufacturing the external semiconductive layer 1, it is usually manufactured not in one piece but in three parts. The reason is that if it is manufactured as an integral product, the inner mold cannot be removed after the integral product is molded. Figure 4 shows Figure 3
1a and 1b are external semiconductive layers which are separately manufactured, 6 indicates a joint thereof,
“a” indicates a seam on the outer surface side of the external semiconductive layer.

FIG. 5 is a longitudinal sectional view of a main part of a power cable connecting portion using a pre-molded rubber insulator 4. As shown in the figure, for example, a connection portion 13 of a conductor 11 of a plastic insulated power cable 10 such as a cross-linked polyethylene insulated power cable is included, and a preform is provided over both cable insulating cores 12 to be connected. A rubber insulator 4 is provided.

The procedure for forming a power cable connecting portion using the pre-molded rubber insulator 4 is as follows. The inner diameter of the pre-molded rubber insulator 4 is smaller than the outer diameter of the cable insulating core. , Pre-molded rubber insulator 4
A large diameter jig is inserted into the inside hollow portion of the preform rubber insulator 4 so that the inside diameter of the pre-molded rubber insulator 4 is largely enlarged, and is released onto one of the cables before the formation of the cable conductor connection portion 13. deep. After the cable conductor connecting portion 13 is formed, the pre-mold rubber insulator 4 is returned onto the cable conductor connecting portion 13 and the diameter increasing jig is pulled out, so that the pre-mold rubber insulator 4 is removed. It is attached to the outer surface of the cable insulating core 12 by elastic force.

[0006]

FIG. 4 shows a joint 6 between external semiconductive layers of the conventional pre-molded rubber insulator 4 which are separately manufactured. As is clear from the figure, the outer surface side joint 6a between the tip of the external semiconductive layer 1a and the external semiconductive layer 1b is perpendicular to the central axis direction of the pre-molded rubber insulator.

Therefore, when the diameter of the pre-molded rubber insulator 4 is increased when forming the power cable connecting portion, the outer surface side which is perpendicular to the center axis direction of the pre-molded rubber insulator. The joint 6a receives the force in the direction of the arrow. When the force in the direction of the arrow is received, the outer surface side joint 6a is opened, and this sometimes causes the outer semiconductive layer 1b to tear in the radial direction.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and is characterized in that an external semiconductive layer provided on the outer periphery of an insulating layer in a pre-molded rubber insulator has a radially divided portion. The joint on the outer surface side of the divided portions is such that the tip of one outer semiconductive layer overlaps the outer surface of the other outer semiconductive layer and is in the same direction as the central axis direction of the pre-molded rubber insulator. It was formed in.

[0009]

FIG. 2 is a longitudinal sectional view of a pre-molded rubber insulator for a power cable connecting portion according to the present invention. FIG.
3, the same reference numerals as those in FIG. 3 indicate the same parts, and the difference from FIG.

FIG. 1 is an enlarged view of part B of FIG.
Reference numerals 1c and 1d denote external semiconducting layers which are separately manufactured.
Denotes a seam, and 7a denotes a seam on the outer surface side of the external semiconductive layer. As shown in FIG. 1, the tip of the external semiconductive layer 1d is formed so as to overlap the outer surface of the external semiconductive layer 1c. That is, the joint 7a on the outer surface side is formed so as to be in the same direction as the central axis direction of the pre-molded rubber insulator.

Therefore, when the diameter of the pre-molded rubber insulator 4 is expanded in forming the power cable connecting portion, a force for opening the seam is applied to the seam 7a on the outer surface side. It will not be. Rather, due to the elastic force of shrinking in the radial direction, a force for more close contact acts on the joint.

According to the present invention, at the time of the diameter expanding operation,
The force for opening this seam is hardly applied to other seams which are perpendicular to the central axis direction of the pre-molded rubber insulator. This is because the outer semiconductive layer 1d at the seam 7 is made thicker than the conventional one, and therefore receives a stronger elastic force from the outer semiconductive layer 1d to shrink in the radial direction. .

[0013]

As described above, the preform of the present invention is
According to the molded rubber insulator, when the diameter of the pre-molded rubber insulator is expanded when forming the power cable connecting portion using the molded rubber insulator, the joint between the divided portions of the external semiconductive layer is opened. Radial tearing of the resulting pre-molded rubber insulator can be prevented. Therefore, it is possible to obtain not only more economical but also highly stable and highly reliable pre-molded rubber insulator.

[0014]

[Brief description of the drawings]

FIG. 1 is a partially enlarged longitudinal sectional view of a pre-molded rubber insulator for a power cable connecting portion of the present invention.

FIG. 2 is a longitudinal sectional view of a pre-molded rubber insulator for a power cable connecting portion according to the present invention.

FIG. 3 is a longitudinal sectional view of a conventional pre-molded rubber insulator for a power cable connecting portion.

FIG. 4 is a partially enlarged longitudinal sectional view of the pre-molded rubber insulator of FIG. 3;

FIG. 5 is a power cable using a pre-molded rubber insulator 4
It is a longitudinal section of an important section of a bull connection part.

[Explanation of symbols]

 Reference Signs List 1 outer semiconductive layer 1c outer semiconductive layer 1d outer semiconductive layer 2 insulating layer 3 inner semiconductive layer 4 pre-molded rubber insulator 5 injection hole 6 seam 6a outer surface side seam 7 seam 7a outer surface side Seam 8 Central axis of pre-molded rubber insulator 10 Power cable 11 Cable conductor 12 Cable insulation core 13 Cable conductor connection

Continuation of the front page (56) References JP-A-9-308073 (JP, A) JP-A 47-33891 (JP, U) JP-A 4-88327 (JP, U) JP-A 62-24487 (JP , U) Shokai 52-101994 (JP, U) Shokai 63-10729 (JP, U) Shokai 60-42031 (JP, U) (58) Fields surveyed (Int. Cl. ⁷ , DB Name) H02G 15/058 H02G 1/14

Claims (1)

(57) [Claims] An outer semiconductive layer provided on an outer periphery of an insulating layer in a pre-molded rubber insulator has a radially divided portion, and a joint on the outer surface side between the divided portions is one outer semiconductive layer. Characterized in that the end of the pre-molded rubber overlaps the outer surface of the other external semiconductive layer and is formed in the same direction as the central axis of the pre-molded rubber insulator. Rubber insulator.