JPH0328136B2 - - Google Patents

Description

BACKGROUND AND OBJECTS OF THE INVENTION The present invention relates to an OF cable connection, and more particularly to a semi-stop device to be constructed between a cable sheath and a cable core at the connection.

As illustrated in FIG. 1, this type of semi-stop device that has been used conventionally has a lead pipe 3 straddled over a cable sheath 1 made of aluminum and a cable core 2 led out from the end of the sheath 1. Both ends of the lead pipe 3 are placed on the wrapping layers 4, 4 of packing or plastic tape (such as tetrafluoroethylene tape) applied to the sheath 1 and the cable core 2, and the binding wire 5 is attached to the outer periphery of the pipe 3 at both ends. The cable was wrapped around the sheath 1 and the cable core 2 to be pressed and fixed.

However, when the cable is installed at a high head, or when sufficient offset cannot be taken due to manhole restrictions and an imbalance of axial force occurs due to thermal expansion and contraction of the cable, the cable core and sheath behave differently, resulting in The effect appears as a movement phenomenon of the reinforcing insulator of the cable core and the connection part within the connection box, and the stress between the cable core and sheath is concentrated in the semi-stop device part. This stress concentration acts on the attachment portion of the lead pipe 3 on the cable core, causing soft spots in the cable core insulator, which may cause an electrical breakdown accident.

Therefore, in order to prevent the occurrence of the above-mentioned accidents, it is necessary to forcibly restrain the reinforcing insulator at the cable core or the connection part so that it does not move, or to prevent the movement of the cable core and the reinforcing insulator from being restrained. There are two possible ways to create a movable structure.

However, the former of the above methods requires extremely difficult requirements for the OF cable, and is difficult to realize.
In the latter case, as long as the conventional semi-stop method is adopted, it is extremely difficult to achieve both the semi-stop function and the movable function of the cable core, and in particular, it is almost impossible to accommodate the multiple reciprocating movements of the cable core.

SUMMARY OF THE INVENTION In view of the problems of the prior art, it is an object of the present invention to provide a novel semi-stop device for OF cable connections of this type, which allows the cable core to move back and forth within the connection.

[Summary of the Invention] That is, the gist of the present invention is to provide a cylindrical body that is attached to the cable sheath side and extends over the cable core and has an inner diameter larger than that of the cable core type, and a packing member that is attached to the cable core. The packing member has a thin protrusion extending diagonally outward, and with the thin protrusion tilted toward the cable sheath, its maximum outer diameter can slide onto the inner surface of the cylinder. OF characterized by being brought into contact with
Located in semi-stop device for cable connections.

[Embodiment] Fig. 2 shows an embodiment of a semi-stop device for an OF cable connection part of the present invention, in which 1 is a metal sheath such as an aluminum sheath, 2 is housed within the metal sheath 1, and the sheath end is 1a shows a cable core covered with a reinforcing insulator and a core connection formed at the end thereof led out from 1a. Although not shown, a connection box that covers the core connection portion is attached to the end of the cable sheath. Now, the semi-stop device 10 is provided with a cylinder 20 on the metal sheath 1 side and a packing member 30 on the cable core 2 side. That is, a packing layer or a plastic tape wrapping layer 21 made of tetrafluoroethylene or the like is applied to the metal sheath end 1a, and a lead pipe 22 is fitted onto the layer 21 so that a part of it protrudes forward from the sheath end, and is tightened with a binding wire 23. One end of the cylinder 20 is inserted into the front protrusion of the sheath end of the lead pipe 22, and the bind wire 24 is inserted from the outer periphery of the lead pipe 22.
By tightening the metal sheath end 1a, the cylindrical body 20 is made liquid-tight to the metal sheath end 1a and extends over the cable core 2.

On the other hand, a wrapping layer 31 of packing or plastic tape such as tetrafluoroethylene is applied on the cable core 2, and a packing member 3 is applied thereon.
0 is fitted onto the cable core 2, and the binding wire 32 wound around the core 2 is wound around the outer periphery of the packing member and tightened, thereby attaching the packing member 30 to the cable core 2.
It is attached liquid-tightly to the top.

The cylindrical body 20 has an inner diameter larger than the outer diameter of the cable core 2, and has one packing member 3.
A thin protrusion 30a having a maximum outer diameter approximately equal to the inner diameter of the cylinder is provided on the outer circumferential portion of the cylinder. It is tilted toward the sheath end 1a so that its maximum outer diameter portion is fitably in contact with the inner surface 20a of the cylindrical body 1.

With the above structure, oil leakage from the metal sheath 1 side is prevented from occurring between the packing member 30 liquid-tightly attached to the cable core 2 and the metal sheath end 1a.
This can be prevented by mutual contact between the cylindrical bodies 20 that are fluid-tightly attached to the metal sheath 1, and if the oil pressure on the metal sheath 1 side increases even slightly, the thin protrusion 3 of the packing member 20
0a strongly presses into contact with the inner circumferential surface 20a of the cylinder 20 under the influence of hydraulic pressure, thereby achieving an even more reliable oil-stopping effect, and can be used as a temporary oil-stopper when assembling the connection or disassembling the connection in the unlikely event that it occurs. The device is capable of exhibiting sufficient functionality.

In addition, during operation after the cable system is completed, the inside and outside of the semi-stop device have the same hydraulic pressure, so the cylinder body 2 of the thin protrusion 30a of the packing member 30 as described above
Since the pressing force toward 0 disappears, movement caused by unbalance of the axial force of the cable core (including the reinforcing insulator at the connection part) is caused by the packing member 30.
This allows the mutual contact and sliding movement of the cylinder body 20 and the cylinder body 20 to occur more smoothly.

In addition, the multiple reciprocating movements of the cable core that occur during thermal expansion and contraction can be absorbed by the light sliding between the packing member 30 and the cylindrical body 20, so that a stable semi-stop function can be maintained and the cable core 2 can be moved back and forth many times. This will not apply stress to the insulator.

In the figure, l ₁ and l ₂ indicate the movable range of the packing member 30.

It is preferable that the cylinder 20 is made of metal, but any material having the same strength as that can be used, and the packing member 30 may be made of rubber or soft plastic, for example. Adopt a manufactured product.

[Effects of the Invention] As explained above, the semi-stop device for an OF cable connection part of the present invention has a movable structure for the cable core, and the stress applied between the cable and the cable core is transferred between the cylindrical body attached to the sheath and the core. Since the gas is absorbed by the mutual contact and sliding of the packing members installed above, it is possible to prevent the occurrence of negative effects (soft spots, damage to the insulation paper) on the cable core at the semi-stop part, which can lead to serious accidents such as insulation breakdown. However, the cable system as a whole was able to have extremely high reliability, and the practical benefits are enormous.

Furthermore, according to the semi-stop device of the present invention,
You can also expect the following effects.

In other words, since the maximum outer diameter portion of the thin-walled protrusion extending diagonally outward comes into contact with the inner surface of the cylinder on the cable sheath side, even if the cable core and cable sheath are slightly eccentric, the thin-walled protrusion will The pieces can be absorbed by elastic deformation, and there are no functional problems. In addition, since the thin protruding piece also functions as a buffer material, even if the cable core is slightly bent due to the axial force, there is almost no adverse effect on the insulator.

In addition, since this thin-walled protrusion is tilted toward the cable sheath side and its maximum outer diameter portion is in contact with the inner surface of the cylinder on the cable sheath side, the hydraulic pressure outside, that is, inside the connection part, is slightly smaller than the hydraulic pressure inside the cable sheath. However, when raised, the thin protrusion is pushed from the outside and separated from the inner surface of the cylinder, thereby ensuring oil flow from the connection portion into the cable sheath. This means that
When lubricating a cable section sandwiched between cable connections from the connection part, there is no need for a valve to ensure oil flow between the inside and outside of the semi-stop, which was required in conventional semi-stops, and the oiling work can be performed. It is also extremely effective.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional explanatory view showing an example of a conventional semi-stop device for connecting an OF cable, and FIG. 2 is a cross-sectional explanatory view showing an embodiment of the semi-stop device for connecting an OF cable according to the present invention. 1: Metal sheath, 2: Cable core, 10: Semi-stop device, 20: Cylindrical body, 30: Packing member.

Claims (1)

[Claims] 1. A cylindrical body attached to the cable sheath side and extending over the cable core and having an inner diameter larger than the diameter of the cable core, and a packing member attached to the cable core, and the packing member has a cylinder extending diagonally outward. An OF cable characterized in that the OF cable has a thin-walled protruding piece, and the thin-walled protruding piece is tilted toward the cable sheath and its maximum outer diameter portion is slidably in contact with the inner surface of the cylindrical body. Semi-stop device for connection.