Electricity: conductors and insulators – Conduits – cables or conductors – Single duct conduits
Patent
1994-10-26
1997-06-03
Sough, Hyung S.
Electricity: conductors and insulators
Conduits, cables or conductors
Single duct conduits
59 781, 138120, F16L 1100
Patent
active
056356757
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD OF THE INVENTION
This invention relates to a bendable protective tube for buried cables which is used to protect from earth and sand and water an electric cable, such as a power line buried under the ground.
BACKGROUND OF THE INVENTION
A three dimensionally bent tube consisting a conventional protective tube of this kind for buried cables generally consists of a combination of hard two-dimensionally bent tubes having a predetermined radius of curvature (for example, 3 mR, 5 mR and 10 mR), or a hard corrugated polyethylene tube, or a mechanically bent metal tube. However, when such tubes are employed, it is necessary to select bent tubes of a plurality of radii of curvature and cover cables therewith by giving consideration to the directions in which these tubes are bent. Consequently, much labor and technical skill are required. When hard corrugated polyethylene tubes are used, a worker damages a cable in some cases by accidentally piercing his pickax through a thin-walled portion thereof during a cable burying operation.
When metal tubes are used, it is necessary to carry a bending machine into a construction field and repeatedly field-adjust the radii of curvature and bending directions of the metal tubes, so that complicated operations are necessarily carried out in a cable burying place. Consequently, much labor is required, and a construction period is prolonged. Moreover, once in a long while, pipes laid underground are damaged in error by working tools during the engineering work for water supply pipes, sewerage pipes and gas pipes.
SUMMARY OF THE INVENTION
In view of the facts described above, a principal object of the present invention is to provide a bendable protective tube for buried cables, capable of reducing the labor in a cable burying place and a construction period.
The present invention provides a bendable protective tube 1 for buried cables, comprising a plurality of cylindrically formed highly rigid resin tube bodies 4 connected to one another unitarily via resin nodes 5 which are cylindrically bent so as to have a substantially S-shaped cross section, each of the nodes being composed of a rigid portion 2 and a deformable portion 3 covered with and protected by the rigid portion.
These reference numerals are used for the convenience's sake to denote elements corresponding to those shown in the drawings, and the present invention is not limited to what are shown in the drawings.
Owing to the above-described construction, the deformable portions 3 of the nodes 5 are freely deformable, and as a whole for buried cables has a flexibility, the action of an external force imparted to the deformed portions being prevented or arrested by the rigid portions 2.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1A is a front elevation of a bendable protective tube for buried cables according to the present invention 1;
FIG. 1B is a sectional view of the bendable protective tube for buried cables shown in FIG. 1A;
FIG. 2 is a sectional view taken along the line A-A in FIG. 1A of the bendable protective tube for buried cables;
FIG. 3A is a front elevation of the bendable protective tube in a bent state for buried cables shown in FIG. 1;
FIG. 3B is an enlarged section of a part of the bendable protective tube for buried cables shown in FIG. 3A;
FIG. 4 is an enlarged section of a node of a bendable protective tube for buried cables according to a second embodiment of the present invention;
FIG. 5 is an enlarged section of a node of a bendable protective tube for buried cables according to a third embodiment of the present invention;
FIG. 6 is an enlarged section of a node of a bendable protective tube for buried cables according to a fourth embodiment of the present invention;
FIG. 7 is an enlarged section of a node of a bendable protective tube for buried cables according to a fifth embodiment of the present invention; and
FIG. 8 is an enlarged section of a node of a bendable protective tube for a sixth embodiment of the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
Ref
REFERENCES:
patent: 2784989 (1957-03-01), Krupp
patent: 5027665 (1991-07-01), Hayward
Maruho Sangyo Kabushiki Kaisha
Sough Hyung S.
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