JPH09327113A - Adjustable bending pipe for cable protection - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adjustable bending pipe which can be bent by a small external force and which is hardly returned to its original state when the external force is removed. SOLUTION: In an adjustable bending pipe 1 for cable protection, end parts of separate cable protective pipes 11, 12 are inserted from respective ends of a collar pipe 2 whose inside diameter is larger than outside diameters of the cable protective pipes 11, 12, elastic spacers which are interposed in the gap between the cable protective pipes 11, 12 and the collar tube 2 in respective insertion parts are constituted so as to be divided into ring-shaped outside elastic spacers 31, 32 and ring-shaped inside elastic spacers 41, 42, the outside elastic spacers 31, 32 are pasted on the inner circumferential face at the respective ends of the collar pipe 2, and the inside elastic spacers 41, 42 are pasted on the outer circumferential face at the insertion end parts of the cable protective pipes 11, 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible curved tube for protecting a cable used for constructing a bent portion for a protective tube such as an underground power cable.

[0002]

2. Description of the Related Art As a conventional flexible tube for protecting a cable, FRP or PVC is used as a material, and a short tube having a notched spherical receiving portion is fitted into the receiving portion from the inside. In some cases, the short tube whose outer surface is formed into a spherical shape is fitted and integrated with a seal ring.

However, in the conventional flexible tube for cable protection as described above, the diameter of the spherical fitting portion formed to obtain the desired bending angle is about 1.5 times the diameter of the other portions. There is a problem that it becomes large and it is difficult to construct it in a narrow place. Also, since the diameter of the fitting part becomes large, when arranging the pipes of multiple systems side by side in a multi-row / multi-stage arrangement,
There is a problem that the excavation width needs to be widened because the distance between the pipes of other adjacent systems must be wide, and the situation that the excavation ditch does not fit is sometimes caused.

If a curved pipe molded to a predetermined curvature is used instead of a flexible curved pipe, the diameter will not be 1.5 times, but it will flexibly cope with unexpected obstacle avoidance at the construction site. Since this is not possible and it is difficult to respond flexibly during on-site construction, there was a need for a bendable joint that would not increase in diameter.

Therefore, in the application of Japanese Patent Application No. 07-281974, the Applicant, as shown in FIG.
The end of each cable protection tube 111, 112 is inserted from each end of the collar tube 120 having an inner diameter larger than the outer diameter of 11, 112, and the outer peripheral surface of each insertion end and the inner peripheral surface of the color tube 120 are inserted. A flexible curved tube 100 for cable protection was proposed in which an elastic spacer 130 was interposed in the gap between and so that the outer diameter of the joint could be made sufficiently small.

[0006]

However, in the flexible bending tube 100 for cable protection of FIG. 4, since the elastic spacer 130 has a wide width, it is necessary to elastically deform the elastic spacer 130 having a large area when bending. There is room for improvement in that relatively large force is required and that the bending angle tends to return to a small value due to the elastic restoring force when the external force is removed.

In particular, the elastic spacer 130 is a cable protection tube.
Since it is attached to both 111 and 112 and the color tube 120 and cannot slide, the bending angle is formed only by elastically deforming the elastic spacer 130. It requires a relatively large force, and after removing the external force, it easily returns to its original state due to the elastic restoring force.

In view of the above points, the present invention is a further improvement of the above-mentioned application (Japanese Patent Application No. 07-281974) so that it can be bent with a small external force, and when the external force is removed, the original state is restored. The purpose of the invention is to provide a flexible curved tube for protecting the cable that is difficult to return.

[0009]

In the flexible tube for protecting a cable according to the present invention, an end portion of each cable protection tube is inserted from each end of a collar tube having an inner diameter larger than an outer diameter of the cable protection tube. A flexible tube for protecting a cable in which an elastic spacer is interposed in a gap between the cable protection tube and the color tube at each insertion portion of the ring tube, the elastic spacer being attached to the inner peripheral surface of each end of the color tube. And an annular inner elastic spacer attached to the outer peripheral surface of the insertion end of the cable protection tube.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a flexible tube for protecting a cable according to the present invention will be described in detail with reference to the drawings showing an embodiment thereof. FIG. 1 is a sectional view showing a flexible tube for protecting a cable according to the present invention. In FIG. 1, reference numeral 1 is a flexible curved tube for cable protection of the present invention, and 11 and 12 are cable protection tube bodies. Reference numeral 2 denotes a collar tube having an inner diameter larger than the outer diameters of the cable protection tubes 11 and 12, and the end portions of the cable protection tube bodies 11 and 12 are inserted into the respective ends of the color tube 2.

31 and 32 are annular outer elastic spacers,
The cable protecting tubes 11 and 12 are interposed between the outer peripheral surfaces of the insertion ends and the inner peripheral surface of the collar tube 2 and are attached to the inner peripheral surfaces of the respective ends of the collar tube 2. The outer elastic spacers 31, 32
The outer peripheral surface of the cable is firmly adhered to the inner peripheral surface of the color tube 2 by an adhesive or the like to be integrated, and the inner peripheral surface is formed with a concavo-convex structure composed of grooves and ridges in the circumferential direction. It is in sliding contact with the outer peripheral surface.

41 and 42 are annular inner elastic spacers,
Similar to the outer elastic spacers 31 and 32, they are interposed between the outer peripheral surfaces of the insertion ends of the cable protection tubes 11 and 12 and the inner peripheral surface of the collar tube 2 to insert the insertion ends of the cable protection tubes 11 and 12. Is attached to the outer peripheral surface of the. The inner peripheral surfaces of the inner elastic spacers 41 and 42 are firmly adhered to the outer peripheral surfaces of the cable protection tubes 11 and 12 with an adhesive or the like to be integrated, and the outer peripheral surface has irregularities composed of circumferential grooves and ridges. The structure is formed and slidably contacts the inner peripheral surface of the color tube 2.

The cable protection tubes 11 and 12 and the color tube 2
It is preferable to use PVC, FRP, FRPM, or the like as the material of, and rubber, foam rubber, urethane resin, PE foam, PVC foam, or the like as the material of the elastic spacer.

Hereinafter, a case where a curved pipe portion is constructed by using the flexible curved pipe for cable protection according to the present invention will be described with reference to FIG. When the flexible cable for cable protection having the above-described structure is bent, the outer peripheral surface of the inner elastic spacer 41 adhered to the insertion end of the cable protective tube 11 slides on the inner peripheral surface of the color tube 2 and the A bending angle θ is formed as shown in FIG.

At this time, the portion A of the inner elastic spacer 41 slides toward the outer elastic spacer 31 and is compressed. When the portion A of the inner elastic spacer 41 slides along the inner surface of the color tube 2, the portion B of the cable protection tube 11
Slides along the inner peripheral surface of the outer elastic spacer 31. Then, the outer elastic spacer adhered to the end of the color short tube 2
The portion C of 31 is pressed against the cable protection tube 11 and compressed.

In this way, a large amount of force is not required to bend since the curved pipe portion is constructed while the unbonded surface of each elastic spacer slides on the surface of each pipe. Then, when the external force is removed, even if it tries to return to the original state by the elastic restoring force, since the uneven structure is formed on the sliding contact surface between each elastic spacer and the surface of each tube, a large friction resistance acts, It is difficult to return to the original state.

The bending angle θ is tan ⁻¹ (d / θ) when the distance between the outer elastic spacer 31 and the inner elastic spacer 41 is S and the difference between the thickness of the portion A and the thickness of the portion B is d. So
By setting the Young's modulus of the elastic spacer and the distance S, the maximum bending angle per set of flexible bending tubes for cable protection is determined. A larger bending angle can be obtained depending on how many sets of the flexible cables for protecting the cable shown in FIG. 1 are connected.

In the curved pipe portion constructed in this manner, the inner and outer sides of the pipe are doubly shielded by the inner elastic spacer 41 and the outer elastic spacer 31, so that the power cable laid inside the pipe is Be protected reliably.

A case where a large bending angle is obtained by connecting the flexible curved tubes for cable protection of the present invention in multiple stages will be described below with reference to FIG. In FIG. 3, when four flexible bending tubes for cable protection having the configuration shown in FIG. 1 are connected and five cable protection tubes 11, 12, 13, 14, and 15 are connected to form a bending tube, A cross-sectional view is shown.

In this case, if the bent flexible tubes for cable protection are bent and held at both ends, the lever principle also works,
It can be easily bent by the force of the arm to set a desired bending angle.

According to the flexible tube for cable protection of the present invention, the length and length of the cable protection tube and the collar tube are shortened to obtain a smaller curvature, without being limited to the dimensions and materials described above. Therefore, it is possible to obtain a larger bending angle by increasing the number of the cable-bending flexible bending tubes to be connected. That is, it is possible to easily obtain a desired curvature and bending angle by variously setting the Young's modulus of the elastic spacer and the dimensions of each part.

Further, the outer diameter of the bendable joint can be made sufficiently small, and even if the cable protection tubes are arranged in multiple rows / multistages, the space between the universal joints can be sufficiently narrowed, and the cable protection tubes in multirow / multistage arrangements Since the width and depth of the groove for accommodating the groove can be reduced by that much, excavation work and backfilling work of the groove are facilitated. Also, even if the cable protection tube of the flexible bending tube for cable protection is a straight tube, a sufficiently large bending angle can be guaranteed and stable support by the tube pillow becomes possible.

Furthermore, since cut pieces of ordinary pipe material can be used for the color tube and the cable protection tube, it is possible to provide an inexpensive flexible tube for cable protection.

[0024]

[Embodiment] In the configuration of FIG. 1, when rubber is selected as the material of the elastic spacer and three cable protection tubes are connected using one color tube, that is, one set of flexible cables for cable protection is used. A bending angle of 9.52 ° was obtained with the tube. In the configuration of FIG. 3, the length of the cable protection tube 11 is 20
When the length of the color tube 2 was set to 0 mm and the length of the color tube 2 was set to 150 mm, and five cable protection tubes were connected by four sets of flexible tube for cable protection, a bending angle of about 38 ° was obtained as a whole.

[0025]

According to the flexible tube for cable protection of the present invention, when the external force is removed after the bending angle is set to a predetermined value, even if the elastic restoring force of the compressed elastic spacer acts, the elastic tube is elastic. Since the bending angle does not become small unless it slides against the frictional resistance between the spacer and the surface of the tube, it is difficult to return to the original state, and the effect that the set state is easily maintained is obtained.

Further, since it can be bent with a small force, the workability can be improved. further,
Since each elastic spacer is attached to only one tube, it is possible to expand and contract slightly at the bendable joint,
It is also possible to make corrections in the length direction according to the situation at the work site.

Further, since a double spacer consisting of an outer elastic spacer and an inner elastic spacer is interposed in the bendable joint, it is possible to reliably prevent water and earth and sand from entering the cable protection tube, and to prevent the cable from entering. Smooth withdrawal, removal,
It is possible to guarantee renewal.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an embodiment of a flexible tube for protecting a cable according to the present invention.

FIG. 2 is a cross-sectional view of a main part in a bent state.

FIG. 3 is a cross-sectional view in the case where the flexible curved tubes for protecting the cable are connected in multiple stages.

FIG. 4 is a cross-sectional view of a conventional flexible tube for protecting a cable.

[Explanation of symbols]

 1 Flexible bending tube for cable protection 11 Cable protection tube body 11 Cable protection tube body 2 Color tube 31 Outer elastic spacer 31 Outer elastic spacer 41 Inner elastic spacer 41 Inner elastic spacer

Claims (1)

[Claims] 1. An end portion of each cable protection tube is inserted from each end of a collar tube having an inner diameter larger than the outer diameter of the cable protection tube,
In a flexible tube for cable protection in which an elastic spacer is interposed in the gap between the cable protection tube and the color tube in each of these insertion portions, the elastic spacer is attached to the inner peripheral surface of each end of the color tube. An annular outer elastic spacer,
A flexible curved tube for cable protection, comprising an annular inner elastic spacer attached to the outer peripheral surface of the insertion end of the cable protection tube.