JPH11287935A - Cable and installation method - Google Patents

Abstract

(57) [Problem] To provide a cable and a laying method capable of reducing friction between the cable and the pipe and reducing tensile tension when laying the cable in the pipe. A tube (2) containing an empty or cable core (1) and an outer coating (5) on the outside thereof are provided. A plurality of fluid outlets (6) are provided on the surface of the outer coating (5) in the longitudinal direction. The cable has a fluid passage 3 communicating with the fluid outlet 6 and allowing the fluid to flow in the longitudinal direction, inside the outer coating 5 or within the coating thickness in the longitudinal direction. In laying the cable in the pipe 9, the cable is laid in the pipe 9 while the fluid is blown out from the fluid outlet 6 of the outer coating 5 into the pipe 9 through the fluid passage 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cable and a cable laying method capable of reducing the laying tension when the cable is laid in a pipeline.

[0002]

2. Description of the Related Art Various cable structures, laying methods, and the like have been studied in connection with requirements for laying optical fiber cables in sewers and other sewers. There is also a method of laying an optical fiber cable directly in the sewer pipe, but in this case the sewage flows around the cable, so it is necessary to reinforce the armor etc. on the cable itself, the weight is large, and the cable price is high .

[0003] There is also a method of arranging a pipeline in a sewer and laying a cable such as an optical fiber cable in the pipeline. However, when a cable is drawn into the pipeline, the tension between the cable and the pipeline is limited. The cable itself must be able to withstand that tension.
In a conventional cable, the tensile strength of the cable is enhanced by, for example, using a cable structure in which a tensile member is disposed at the center and an optical fiber core is disposed around the tensile member. However, since this kind of cable requires a thick tensile member, the cable outer diameter increases, and the cable price also increases.

[0004] There is also a laying method in which an empty pipe is laid in advance, and a cable is fed through an air flow therein. In this case, no special strength member is required for the cable, but since the cable is sent in an air stream, the weight of the cable is limited, and it is difficult to lay a thick cable.

[0005]

When laying a cable in a pipeline, it is necessary to provide the cable with a thick tensile member as described above. Further, in the method of feeding the cable by carrying it in an air flow, the weight of the cable is limited, and the method cannot be applied to a cable having a large outer diameter. The present invention
It is an object of the present invention to provide a cable and a method of laying a cable in a pipe, which can reduce friction between the pipe and the cable.

[0006]

The cable of the present invention has a tube containing an empty or cable core and an outer coating on the outside thereof, and a plurality of fluid outlets in the longitudinal direction are formed on the surface of the outer coating. And a fluid passage communicating with the fluid outlet and allowing the fluid to flow in the longitudinal direction, the fluid passage being provided inside the outer coating or in the coating thickness over the longitudinal direction.

A cable having an outer coating provided with a plurality of fluid outlets in the longitudinal direction of the surface and having a fluid passage communicating with the fluid outlet inside the outer coating or in the thickness of the coating is provided. In laying the cable, the cable is laid in the conduit while the fluid is blown out from the fluid outlet of the outer coating into the conduit through the fluid passage, thereby reducing friction between the conduit and the cable. Will be possible. Therefore, in this type of cable, the strength member can be made thinner, and in some cases, there is no need to provide a special strength member.

In laying the cable, a sealing portion for sealing a space between the cable and the inner wall of the conduit is attached to a retracted end fixed to the end of the cable.
By laying the cable in the conduit while applying forward pressure to the seal portion by the fluid blown out from the fluid outlet of the outer coating into the conduit through the fluid passage to increase the cable laying propulsion force, Further, the tension required for laying the cable can be reduced.

As the fluid to be blown into the pipe from the fluid outlet of the outer coating through the fluid passage, air or water is cheap and suitable. In the case of air, buoyancy is generated in the cable by the air flow blown from the surface of the cable outer coating, and as a result, friction between the pipeline and the cable can be reduced. In the case of water, the water blown out from the outer coating of the cable serves as a lubricant and can reduce the frictional force.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a view showing a cable of the present invention laid in a pipeline, and FIG. 1 (A) is a side view showing the pipeline opened in a longitudinal section. , FIG. 1 (B)
Is a cross-sectional view. In FIG. 1, 1 is a cable core,
2 is a tube, 3 is a fluid passage, 4 is an upper winding, 5 is an outer coating, 6 is a fluid outlet, 7 is a tension member, 8 is a cable according to the present invention, and 9 is a conduit. The cable core 1 may or may not be inside the tube 2. Further, the number of tubes 2 is not limited to four.

Although the fluid passage 6 is shown in the form of a pipe having a hole communicating with the fluid outlet 6, it is not limited to the pipe, but is formed with a space through which a fluid can flow in the longitudinal direction. I just want it. It is also possible to provide the fluid passage 3 inside the coating thickness of the outer coating 5.

As shown in FIG. 1, the fluid outlet 6 is formed by arranging holes having an inner diameter of about 2 mm in the longitudinal direction and the circumferential direction of the cable 8 at intervals of about 4 mm on the surface of the outer coating 5. Depending on the type of fluid flowing, the length and weight of the cable, there may be no arrangement in the circumferential direction but only the arrangement in the longitudinal direction. In some cases, the interval between the fluid outlets is as wide as several meters. In addition, by forming the fluid outlet at a slight angle from the radial direction of the cross section so as to face obliquely rearward with respect to the cable traveling direction, it is possible to apply a propulsive force to the cable by the fluid outlet. It should be noted that the tension member 7 can be a thinner tension member than the prior art cable, depending on the degree of reduction in friction between the cable and the conduit due to fluid blowing.

When air is used as the fluid and air blows out from the fluid outlet to impart buoyancy to the cable to reduce the friction between the cable and the pipeline, the lower portion where the cable and the pipeline are in contact with each other is required. Since it is necessary to blow air from the fluid outlet, the fluid outlet is also arranged in the circumferential direction of the cable so that the fluid outlet always exists below the cable even if the cable rotates around the axis. Need to be kept. In this case, air is also blown out from the fluid outlet located above the cable, but since the gap above the cable is large, there is no hindrance to the buoyancy applied to the cable.

When the friction between the cable and the pipeline is to be reduced by the water blown out from the fluid outlet using water as the fluid, the fluid outlet is not necessarily required in the circumferential direction of the cable. It is sufficient that the fluid outlets are arranged in the longitudinal direction of the cable. In addition, when the friction between the cable and the pipeline is to be reduced by the oil blown out from the fluid outlet using a lubricant such as oil as a fluid, it is sufficient to arrange the fluid outlets every few meters. It is.

The supply of the fluid to the fluid passage of the cable can be performed from either the leading end of the cable or the trailing end of the cable. Since it is inconvenient to extend the pipe for supplying the fluid to the rear end of the cable, it is preferable to perform the operation from the rear end of the cable using a fluid supply device installed on the rear end side of the cable.

FIG. 2 is a view showing an embodiment of the present invention in which a seal portion is attached to a cable lead-in end, and the same reference numerals as those in FIG. 1 denote the same components. In FIG. 2, reference numeral 10 denotes a seal portion, 11 denotes a cable lead-in end portion, and 12 denotes a drawstring. The seal portion 10 can be a flange-shaped object made of metal, plastic, or the like, but the one made of an elastic body such as a rubber sheet can be used even if the cable drawing end is not located at the center of the pipe. It is preferable because the sealing effect can be maintained by the deformation. When the seal portion 10 is a rigid flange-shaped object, the cable pulling end portion 11 moves along the central axis of the conduit 9, so that the tip moves in the form of lifting the neck. There is no particular problem in cable laying.

In the case where the seal portion is provided, the fluid blown out from the fluid outlet 6 of the cable 8 accumulates on the rear side of the seal, and can act as a pressure for pushing the seal portion forward. The supply of the fluid to the fluid passage inside the cable provided with the seal portion is performed from the rear end of the cable.

[0018]

According to the cable of the present invention, a plurality of fluid outlets are provided in the surface of the outer coating in the longitudinal direction, and the fluid outlet is provided through the fluid passage provided in the outer coating or in the thickness of the coating over the longitudinal direction. By blowing out the fluid, the friction between the conduit and the cable can be reduced, and the tensile tension during laying can be reduced. Therefore, the diameter of the tension member provided in the cable can be reduced.

Further, a seal portion for sealing a space between the cable and the inner wall of the conduit is attached to the drawn end portion of the cable, and forward pressure is applied to the seal portion by the fluid blown into the conduit from the fluid outlet. If the cable is laid in the pipeline while increasing the cable laying propulsion,
Further, the tension required for laying the cable can be reduced.

It is preferable that air or water is inexpensive, abundant, and pollution-free, as the fluid to be blown into the pipeline from the fluid outlet. In the case of air, buoyancy is generated in the cable by the air flow, and in the case of water, the water blown out from the outer coating of the cable serves as a lubricant,
In any case, the frictional force can be reduced.

[Brief description of the drawings]

1A and 1B are diagrams showing an embodiment of a cable according to the present invention, in which FIG. 1A is a side view showing a state where a pipe laid in a pipe is opened in a longitudinal section, and FIG. It is a cross-sectional view in which the cable in the pipeline was laid.

FIG. 2 is a longitudinal sectional view showing an embodiment of a laying method of the present invention in which a seal portion is attached to a cable lead-in end.

[Explanation of symbols]

 1: Cable core 2: Tube 3: Fluid passage 4: Top winding 5: Outer coating 6: Fluid outlet 7: Tension member 8: Cable according to the present invention 9: Pipe line 10: Seal portion 11: Retraction end 12: Tow rope

Claims (5)

[Claims] 1. A tube containing an empty or cable core and an outer coating on the outside thereof, and a plurality of fluid outlets are provided in the surface of the outer coating in a longitudinal direction. A cable, characterized in that it has a fluid passage longitudinally inside said outer coating or within the coating thickness, for communicating the fluid in the longitudinal direction. 2. A cable having an outer coating provided with a plurality of fluid outlets in a surface longitudinal direction and having a fluid passage communicating with the fluid outlet inside the outer coating or in the thickness of the coating. When laying the cable in the passage, the cable is laid in the conduit while the fluid is blown out from the fluid outlet of the outer coating into the conduit through the fluid passage. 3. When the cable is laid, a sealing portion for sealing a space between the cable and an inner wall of a conduit is attached to a retracted end portion fixed to a distal end of the cable, and the outer coating is provided through the fluid passage. 3. The cable according to claim 2, wherein the cable is laid in the conduit while the forward pressure is applied to the seal portion by the fluid blown out from the fluid outlet into the conduit to increase the cable laying propulsion force. How to lay. 4. The method of laying a cable according to claim 2, wherein the fluid blown into the conduit from the fluid outlet of the outer coating through the fluid passage is air. 5. The method of laying a cable according to claim 2, wherein the fluid blown into the pipe from the fluid outlet of the outer coating through the fluid passage is water.