JPS5942531B2 - Structure of fire-resistant and heat-resistant cable connections - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a structure of a connection part in a fireproof and heatproof cable.

In general, there are branch connections and straight connections for power transmission and communication cable connections, and the connections of cables that are made fireproof and heat resistant by a heat-resistant layer have a special connection structure to support fire and heat resistance. has been adopted.

The structure of a connecting portion in a conventional fire-resistant and heat-resistant cable is shown in FIGS. 1 to 4.

Figure 1 shows the partial processing structure of the core wire connection part.
The core wire 3 exposed from the heat-resistant sheath 2 of the cable 1, 1,
3 with a crimp sleeve 4, a fire-resistant or heat-resistant tape 5 is wrapped around the crimp sleeve 4 and the heat-resistant sheath 2, and a self-fusing tape 6 and an adhesive vinyl tape 7 are applied over this to insulate the cables 1 and 1. The connecting portion A is formed by winding the wire in order until it covers the body 8.

FIG. 2 shows a first example of a sheath connection structure applied to the outer periphery of the core wire connection portion shown in FIG. Collect the wires 3 and apply self-adhesive tape 9 and adhesive vinyl tape 1 again to the outside of the whole.
0 is wound around the outer circumference of the end of the cable 1.

A second example of the jacket connection structure shown in FIG. 3 uses a metal box 11, and a connection portion A having the same structure as that in FIG. 1 is housed in this box 11.

The third example of the structure of the jacket connection part shown in FIG. 4 is the connection part A.
This is a case where the outside of the is molded with an insulator 12.

However, in the structure of the connection part, which is finished by wrapping various tapes in sequence as described above, there is a difference in moisture resistance depending on the taping skill, and not only is it not possible to obtain uniform connection performance (but the moisture resistance is generally poor). There are drawbacks.

In addition, the work is difficult because various tapes must be wound into complicated shapes, and connections by winding tapes do not provide sufficient strength, and cables tend to come off when tensile loads are applied (low mechanical strength There is a problem.

In addition, the structure that uses a box is completely moisture-proof (
Not only is this not taken into consideration, but it is also unsuitable for branch connections of multicore cables in terms of structure and space.

Furthermore, in the case of the mold type, it is necessary to use materials with excellent fire resistance, but such special materials are not commercially viable and cannot be easily obtained, so there is the problem that connections cannot be easily made. be.

This invention was made in order to eliminate the above-mentioned problems and drawbacks, and provides a connection structure that has a simple structure, has excellent moisture resistance and mechanical strength, and can improve fire resistance and heat resistance. The purpose is to provide.

Hereinafter, an explanation will be given based on FIGS. 5 and 6 showing an embodiment of the present invention.

Figure 5 shows an example of application to a single branch connection, where the cable 21
In this case, the cable sheath 23 is peeled off over a predetermined length at a desired connection position of the branch cable 22, and the sheath is also peeled off from the end of the branch cable 22.

The core wire 24 of the cable 21 to be branched and the core wire 25 of the branch cable 22 are connected by a connecting portion 26 using a means such as a crimp sleeve or soldering.

A spacer tape 27 is wound around the outer periphery of both ends of the cable 21, sandwiching the peeled portion of the cable sheath 23.

This tape 27 is wrapped over the sheath of the branch cable 22 along the cable 21.

A lead pipe 28 that integrally covers the cable 21 and the branch cable 22 is inserted into the portion of the cable 21 from which the cable sheath 23 has been peeled off.

This lead pipe 28 has a length that reaches the spacer tapes 27 on both sides at both ends, and a space 2 sufficient to surround the core wire connection part 26 inside.
9, and both ends thereof are fixed to the outer periphery of the spacer tape 27 by a constricted portion 30 formed by caulking.

At both ends of the lead pipe 28, the lead pipe 28 and the cable 2 are connected.
1 and the branch cable 22 are provided, and a protective layer 3 is provided in which heat shrink tape or adhesive tape is wrapped around the outer periphery of the lead pipe 28 and the outer periphery of the sealed connection part 31.
2 will be applied.

The sealed connection portion 31 is formed using a filler such as epoxy 7 resin, and serves to fix the connection between the lead pipe 28 and the cable 21 and at the same time maintain the moisture-proof property of the connection portion.

Both ends of the protective layer 320 are attached to the cable 21 by a spacer tape 33 wound around the outer periphery of the cable 21 and a self-fusing tape or adhesive vinyl tape 34 wound around the outer periphery of the cable 21.
is fixed.

A first example of the connection part structure of the present invention has the above-mentioned configuration, in which the cable sheaths of the cable 21 and the branch cable 22 are peeled off, the core wires 24 and 25 are connected at the connection part 26, and the outer periphery of the cable 21 is connected. After wrapping the spacer tape 27, the lead pipe 28 is inserted and its both ends are fixed to the spacer tape 27 with the constriction part 30. Next, a filler is adhered to both ends of the lead pipe 28 to form a sealed connection part 31, and then the lead pipe 28 is protected. Layer 32 is provided to complete the connection.

In cables, the main cause of insulation resistance deterioration in the event of a fire is
This is due to strongly ionizing gases such as carbon or chlorine generated when the cable burns.

However, in the connection structure of the present invention, the connection portion is covered with the lead pipe 28.

The melting point of lead is generally as low as about 330°G, and for this reason, the lead pipe 28 melts and falls off the cable 21 in the initial stage of a fire.

Therefore, strongly ionizing gas generated when the cable is burned does not become trapped inside, and the insulation resistance does not deteriorate.

Furthermore, since the lead pipe 28 has sufficient voids 29 formed inside it, even if strongly ionizing gas were to be trapped in the connection, it would be stored in the voids 29 and the concentration would be high enough to cause deterioration of the insulation resistance. The lead pipe 28 will fall off from the cable 21 before this occurs.

Next, a second example shown in FIG. 6 will be explained.

This second example is a case where it is used for linear connection of a cable with a support wire while having fire resistance and heat resistance characteristics, and the same parts as those in FIG. 5 are given the same reference numerals and the explanation is omitted.

As shown in FIG. 6, at the ends of the cables 21 and 21 along which the support wire 35 is placed, each of the groups of core wires 24 exposed from the cable sheath is connected by a connecting portion 26,
The support wire 35 is also connected, and then, as in the case of FIG.
2 are formed in order to make the connection.

Note that the cable connection is not limited to one branch as shown in Figure 5, but multi-branch connections with a similar structure are also possible.
Of course, it is also possible to omit this support line in the case where the support line is included as shown in the figure.

As described above, according to the present invention, the cable connection part is covered with a lead pipe, and both ends of the lead pipe and the cable are fixed with a sealed connection part with a filling material, so that the cable sheath and the lead pipe are firmly fixed and connected in a straight line. Regardless of branch connection, even multi-core cables such as communication cables can be connected while having excellent fire resistance, heat resistance, moisture resistance, and mechanical strength.

In addition, since connections are made using lead pipes with sufficient internal gaps, the lead pipes may melt and fall off in the early stages of a fire.
Since the strongly ionizing gas is stored in the void until it falls off, the insulation resistance does not deteriorate due to the presence of the strongly ionizing gas.

Furthermore, since you just need to insert the lead pipe and secure both ends with sealed connections, you can always obtain a homogeneous connection without the need for special techniques, and it is easy to implement as there is no need for special materials. It is possible to achieve effects such as:

Furthermore, since the outer diameter of the finished portion of the connecting portion of this structure can be kept so small that there is not much difference from the outer diameter of the cable, even if the connecting portion is made in advance, it will not pose any problem during cable installation.

Therefore, it is also possible to use the cable as a pre-branched cable that has undergone branching and connection processing in a factory.

Pre-branching improves the reliability of connections,
This can have effects such as shortening the construction period.

[Brief explanation of drawings]

Fig. 1 is a vertical cross-sectional view showing a partial processing structure of a conventional core wire connection part, Fig. 2 is a cross-sectional view showing a first example of an outer jacket connection structure using the same as above, and Fig. 3 is a longitudinal cross-sectional view showing a partial processing structure of a conventional core wire connection part. A front view showing a second example,
FIG. 4 is an explanatory diagram showing the third example, FIG. 5 is a longitudinal sectional view showing the first example of the invention, and FIG. 6 is a longitudinal sectional view showing the second example. 21... Cable, 24, 25... Core wire, 26... Connection part, 27... Spacer tape, 28... Lead pipe, 29... Void, 30... Squeezed portion, 31... Sealed connection portion, 32... Protective layer.

Claims (1)

[Claims] 1. A lead pipe covering the core wire connection part is inserted into the cable while leaving a gap inside, and a sealed connection part is provided at both ends of the lead pipe and the fitting part of the cable. Fire-resistant, heat-resistant cable connection structure. 2. The structure of a fire-resistant and heat-resistant cable connection portion according to claim 1, wherein the sealed connection portion is formed of a filler such as an epoxy resin.