JP3155208B2 - Prefabricated joint seal structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seal structure for a power cable prefabricated joint.

[0002]

2. Description of the Related Art As a power cable, performance, cost,
CV cables having a crosslinked polyethylene as an insulating layer are widely used because of their advantages in terms of maintenance. When constructing a power line by laying this cable, CV cables of a relatively short length are sequentially connected to make a cable line of a required length. Prefabricated joints are often used from the viewpoint of reducing man-hours and construction time, and improving reliability through factory production. This prefabricated joint is also required to be as small as possible in order to reduce the installation space and the cost. In order to respond to such a demand, the present inventor has designed a unit main body that arranges the inner conductor for connecting the cable conductor at the center and insulates the unit body, and uses a cylindrical outer case itself having square flanges attached to both ends as a mold. By casting an epoxy resin admixture into this, the outer diameter of the insulation unit is reduced to the minimum thickness required to maintain its dielectric strength,
In addition, the connection with the cable protection brackets attached to both ends of the unit body is made by using the bolt holes formed at the four corners of the square flange and the bolt holes on the cable protection bracket side, reducing the installation space and reducing the installation space. We have developed a prefabricated joint that can contribute to cost reduction.

FIG. 3 shows an example of the configuration of a linear joint of a CV cable using this unit main body. In FIG. 1, an inner conductor 2 is arranged and fixed in the center of the axis inside an insulating unit 1, and the outside of the insulating unit 1 is covered with a cylindrical outer case 3 integrated with this. In the insulating unit 1, tapered holes 1 a that open from both sides of the internal conductor 2 toward both ends of the insulating unit 1 are provided. An anticorrosion layer 4 made of a heat-shrinkable tube or the like is provided outside the cylindrical outer case 3. The cable 5 connected by the unit body includes a cable sheath 6, a shielding layer 7, an external semiconductive layer 8, and a cable insulating layer 9.
Are sequentially peeled off in a stepwise manner, and a plug 1 is inserted through a slit wedge 11 at the tip of the exposed cable conductor 10.
2 is firmly fixed.

A stress cone 13 composed of an insulating rubber layer 13a and a semiconductive rubber layer 13b is fitted near the distal end of the cable insulating layer 9. Reference numeral 14 denotes a semiconductive tape winding layer for electrically connecting between the semiconductive rubber layer 13b and the external semiconductive layer 8 of the cable. In the cable protection fitting 15, a stress cone pressing mechanism 16 including a pressing fitting 16a and a spring 16b is arranged. The pressing mechanism 16 connects a bolt 22 between the flange 15a on the cable protection bracket 15 side and the square flange 3a on the cylindrical outer case 3 side.
At the time of connection, the stress cone 13 is pressed by the repulsive force of the spring 16b compressed between the step of the protective fitting 15 and the push fitting 16a, and the tapered surface of the outer surface of the insulating rubber layer 13a is tapered into the tapered hole of the insulating unit 1. 1a to maintain the dielectric strength. The space between the anticorrosion cover 17 and the anticorrosion layer 4 and the cable sheath 6 covering the cable protection fitting 15
They are connected by waterproof covers 18 and 19, respectively. The plugs 12 fixed to the distal ends of the cable conductors 10 are pressed against the inner surface of the inner conductor 2 via multi-contact type contacts 20 such as a multi-ram band attached to the outer periphery of the plugs 12 to form a current flow path. The multi-contact type contact 20 is provided with a number of cuts parallel to the width direction in the conductive leaf spring to form a number of bridges connecting both edges, and these bridges are connected to the center line in the longitudinal direction. It is twisted as a shaft and imparts springiness in the thickness direction, is inserted into a groove on the peripheral surface of the plug 12, and is curved and fixed in a ring shape.

[0005]

In the prefabricated joint having such a structure, the overall size and weight can be greatly reduced as described above. However, the flanges 3a and 3b on the unit body side are square flanges. Since there is an extremely narrow width portion, it is not possible to provide an O-ring storage groove there or take a contact surface of the O-ring. Therefore, as shown in FIG. 3, the end surface of the insulating unit is used as the contact surface of the O-ring, and the O-ring storage groove is formed in the flange 15a on the side of the cable protection fitting corresponding thereto.
The O-ring 21 is stored therein. However, when such a structure is adopted, the interface between the square flange 3a and the insulating unit 1 on the end face of the unit body is outside the O-ring 21, and there is a concern that water may enter the interface from the outside. When the unit body is manufactured by casting the cylindrical outer case 3 itself having square flanges attached to both ends as a mold and casting an epoxy resin admixture into the mold, the interface between the square flange and the insulating unit is in close contact. It is thought that there is little possibility of water infiltration there, but in case of water intrusion, there is a risk of electric discharge and dielectric breakdown. It is desirable to take it.

As one of the means, a square flange 3a on the unit body side and a flange 1 on the cable protection bracket side are used.
It is conceivable to insert a flat packing between the flat packing 5a and the flat packing 5a. When the flat packing is lost, the pressing force of the spring of the stress cone pressing mechanism 16 changes, and the pressure at the interface between the stress cone and the tapered hole of the insulating unit also changes, affecting the insulating performance. Use is not preferred. The present invention has been made in view of such a point, and an object of the present invention is to provide a seal structure of a prefabricated joint that is small, lightweight, low in cost, and high in reliability.

[0007]

According to the present invention, there is provided a seal structure for a prefabricated joint, comprising: a resin molded body; and a flange on a cable protection bracket side provided at one end of a unit body having a flange protruding outward from a vicinity of an end face thereof. In the prefabricated joint, a ring-shaped O-ring storage groove is formed on the outer periphery of the end surface of the resin molded body located inside the flange on the unit body side, and the O-ring is stored in the groove. Is pressed by the flange on the cable protection bracket side to seal the three members of the flange on the unit body side, the resin molded body, and the flange on the cable protection bracket side with the O-ring. Things.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is an insulating unit in which a resin molding is cast with an epoxy resin mixture, and a flange on the unit body side has one or both ends of a cylindrical outer case for housing the insulating unit. Can be applied to the unit body for intermediate connection or terminal connection, which is a square flange attached to the unit.Insulation unit places and fixes the inner conductor at the center, such as a straight connection part or branch connection part of a cable The present invention can be applied to a unit body having a tapered hole that opens from one or both ends of the internal conductor toward the end surface of the insulating unit. Further, the present invention can be applied to a unit body in which the insulating unit is configured by casting an epoxy resin using a cylindrical outer case as a mold. In the present invention, O
The cross-sectional shape of the ring storage groove can be any shape, but it is desirable that the cross-sectional shape be triangular from the viewpoint of machining and performance.

[0009]

Next, an embodiment of the present invention will be described with reference to the drawings. In these drawings, the same parts as those in FIG. 3 are denoted by the same reference numerals. FIG. 1 shows a unit main body for a linear joint of a CV cable used in the present invention, and FIG. 2 shows an end view thereof. In these figures, a rectangular flange 3a is fixed to both ends of the cylindrical outer case 3 by welding or bonding. The insulating unit 1 is made of a resin molding such as an epoxy resin mixture, and the inner conductor 2 and the outer case 3 are made of aluminum or the like. The insulating unit 1 is molded by using an epoxy resin mixture having a similar linear expansion coefficient to aluminum. In this unit main body, for example, a cylindrical outer case 3 is used as a mold, and an inner conductor 2 and a core forming a tapered hole 1a are arranged inside the outer case 3, and an epoxy resin mixture is poured and cured between them. Then, by removing the core, a three-piece structure can be obtained. When the insulating unit 1 is cast, a ring-shaped O-ring housing groove 1b is formed between the outer periphery near both end surfaces of the insulating unit 1 and the inner surface of the square flange 3a. The cross-sectional shape of the ring-shaped O-ring storage groove 1b is triangular.

The inner conductor 2 is basically cylindrical, and the outer surfaces at both ends in the axial direction are gently curved to avoid concentration of an electric field. A cylindrical portion 2a is formed on the inner surface of the inner conductor 2 from both ends to the vicinity of the center thereof to receive the plug 12 through the above-mentioned multi-contact type contact. A plug-side rib receiving portion 2b for receiving the plug-side rib (not shown) is formed. Internal conductor side ribs 2c are formed on both sides of the plug side rib receiving portion 2b. These plug side ribs and internal conductor side ribs 2
“c” is an arc-shaped projection having a length of about 90 ° in the circumferential direction of the inner conductor 2 and is engaged with each other when a cable is inserted to form a cable retaining portion. In the unit body having such a configuration, the plug 12 attached to the tip of the cable conductor 10 is connected to the multi-contact type contact 20 as in the case of FIG.
Is inserted into the cylindrical portion 2a of the internal conductor 2 through the hole. Also,
At both ends of the unit body, the cable protection bracket 15 can be attached by connecting the flange 15a on the cable protection bracket 15 side to the square flange 3a with bolts 22. However, as shown in FIG. 1, the O-ring 21 has a ring-shaped O-ring housing groove 1b formed between the outer periphery near both end surfaces of the insulating unit 1 and the inner surface of the square flange 3a.
Is stored inside.

In this case, by tightening the bolt 22, the O-ring is pressed by the flange 15a on the cable protection bracket side, thereby sealing between the rectangular flange 3a, the insulating unit 1, and the flange 15a on the cable protection bracket side. 3, the spring 16b of the stress cone pressing mechanism 16 is tightened by the bolt 22.
Is compressed between the step of the protective fitting 15 and the push fitting 16a, and the repulsive force presses the stress cone 13 to press the tapered surface against the tapered hole 1a of the insulating unit 1 to maintain the dielectric strength. As described above, in the prefabricated joint seal structure of the present invention, the seal between the unit main body and the cable protection metal fitting connected to the unit main body is formed between the outer periphery near both end surfaces of the insulating unit 1 and the inner surface of the square flange 3a. Since the O-ring 21 is accommodated in the O-ring accommodating groove 1b formed therebetween, the rectangular flange 3a, the insulating unit 1, and the flange 15a on the cable protection bracket side are sealed together. Water or the like may enter the interface between the outer periphery near both end surfaces of the insulating unit 1 and the inner surface of the square flange 3a, thereby deteriorating the electrical characteristics and eliminating the fear.

In the present invention, the cross-sectional shape of the O-ring accommodating groove can be any shape, but it is preferable that the cross-sectional shape be triangular from the viewpoint of machining and performance. That is, when the cross-sectional shape of the O-ring storage groove is rectangular, the corner portion thereof is 90 °, which is a starting point, and the insulating unit is easily cracked.
If the cross section is triangular as shown in (1), the corners are obtuse and cracks are unlikely to occur. Also, if the cross section is triangular, even if burrs remain at the separation point between the square flange 3a and the insulating unit 1, the burrs are acute and narrow, so that the O-ring does not enter. Further, in the above description, an example in which the present invention is applied to a straight connection of a CV cable has been described. However, the present invention is not limited to this, and can be applied to a prefabricated branch connection portion or a terminal connection portion. That is, for example, the present invention can be applied to a unit body for terminal connection having a rectangular flange projecting outward from the lower end surface by casting an epoxy resin mixture in a conical cylindrical shape. The effect of can be obtained. In the above description, an example in which a quadrangular flange is used as the flange on the unit body side has been described. However, this may be a hexagonal or other rectangular polygonal flange. In addition, as a resin molded body, an example of casting and manufacturing an epoxy resin admixture has been described,
This may be manufactured using another resin material or another manufacturing method.

[0013]

As described above, according to the present invention, a small size
A seal structure of a prefabricated joint that is lightweight and low in cost and has high reliability can be provided.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view illustrating a unit main body used in the present invention (a sectional view taken along line AA ′ in FIG. 2).

FIG. 2 is a front view of the structure shown in FIG. 1;

FIG. 3 is a longitudinal sectional view illustrating a straight joint of a conventional CV cable.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Insulation unit 1a ... Tapered hole 1b ... O-ring accommodation groove 2 ... Inner conductor 3 ... Cylindrical outer case 3a ... Square flange 5 ... CV cable 12 ... Plug 15 ... Cable protection fitting 21 ... O ring

Claims (5)

(57) [Claims] 1. A prefabricated joint in which a flange on a cable protection bracket side is connected to one end of a unit main body having a resin molded body and a flange protruding outward from the vicinity of an end face thereof. A ring-shaped O-ring accommodating groove is formed on the outer periphery of the end surface of the resin molded body located inside, an O-ring is accommodated in this groove, and the O-ring is pressed by a flange on the cable protection metal fitting side to thereby form the unit. A seal structure for a prefabricated joint, wherein the O-ring seals a gap between a flange on a main body side, the resin molded body, and a flange on a cable protection fitting side. 2. A resin molded body is an insulating unit formed by casting an epoxy resin admixture, and a flange on a unit body side is a square flange attached to one or both ends of a cylindrical outer case for housing the insulating unit. The seal structure for a prefabricated joint according to claim 1, wherein: 3. An insulating unit, wherein an inner conductor is arranged and fixed in the center, and a tapered hole which opens from one or both ends of the inner conductor toward an end surface of the insulating unit is provided. 3. The seal structure of the prefabricated joint according to 2. 4. The seal structure for a prefabricated joint according to claim 2, wherein the insulating unit is formed by casting an epoxy resin mixture using the cylindrical outer case as a mold. 5. The seal structure for a prefabricated joint according to claim 1, wherein the O-ring housing groove has a triangular cross section.