GB1594321A

GB1594321A - Method and device for the liquid tight sealing of the ends of cable conduits

Info

Publication number: GB1594321A
Application number: GB448978A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1977-02-07
Filing date: 1978-02-03
Publication date: 1981-07-30
Also published as: JPS5398089A; DE2805059A1; FR2379928A1; AU3302578A; JPS6037683B2; DE7803504U1; CA1082620A; FR2379928B3

Description

(54) METHOD AND DEVICE FOR THE LIQUID TIGHT SEALING OF THE ENDS OF CABLE CONDUITS (71) We, TADAO HANAOKA AND TAKEO IANAOKA, both of 2470 Oaza Makikou, Nishikanbara-gun, Maki-machi, Niigata-ken, Japan and of Japanese nationalities, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be yarticularly described in and by the follow ing statement: The present invention relates to a method and device for liquid tight sealing of the ends of cable conduits, e.g. for an underground cable. Particularly the present invention re lates to an improved method and device for liquid tight sealing of.a cable conduit end, but at the same time permitting the cable to slide with little friction.

Usually, an underground cable for telecommunications etc. is laid in through a -cableprotecting conduit (cable pipe) which connects between one cable pit and the next.

This cable pit is often subject to flooding ar other flows of water resulting in stagnant water which would penetrate the cable con dust. Thus it would cause cable damage or electrical failures. To avoid such damage or failure, some packing or sealing materials have been applied to the cable conduit where it opens into the cable pit. however, such packing material will harden and contract after a number of years, resulting in a loose packing or sealing and finally deading to falling away of the sealing material from :the cable conduit end through .tremors and vibrations caused for example, by traffic.

.Furthermore, .a mere rigid water tight seal has conventionally been considered as desirable for sudh sealing. Even if a.rigid seal is achieved the cable would be subject.to.a serious damage since such a rigid seal does not permit the cable to .slide backwad .and forwards; i.e. uninterrupted reciprocating axial movements (lmm--lOmm/each move menu) of the cable are usually vital to cables such as telephone cables or the like. Thus there is much.to.be desired in the conventional seal for the end of the cable conduit.

The present invention seeks to provide a new liquid tight sealing method and device for the end of a cable conduit.

According to a first aspect of the invention, there is provided a method of liquid tight sealing the ends of cable conduits comprising fitting onto .the cable a resilient cylinder sandwiched between plates with a lubricating substance applied between the cable and cylinder, inserting the resilient cylinder into .the end of the conduit and thereafter bolting together the plates so as to compress the .resilient cylinder axially and expand the cylin der radially to engage the cylindrical surface with the inner surface of the conduit to retain the cylinder therein.

According to a second aspect of the invention, there is provided a sealing device for liquid tight sealing of the ends of cable conduits comprising a resilient cylinder and two apertured plates for fitting on to the .cable means for lubricating the interface between cable and device and means for bolting the two plates together to axially compress the cylinder and thus cause radial expansion thereof.

The resilient cylinder.and the plate may have.a through hole to receive a cable and at least one longitudinal slit.

The device may comprise a plurality of ringlike protuberances circumferential of the cylinder. The invention will now be described in greater detail by way of example, with reference to the drawings, in which: Figure 1 shows an exploded perspective view of.an embodiment.of the invention; Figure 2 shows a longitudinal sectional view of the embodiment shown in Figure 1 when assembled; Figure 3 shows a longitudinal sectional view of the .device shown in Figure 1 in use; Figure 4 shows a side view 'of a further embodiment of the invention; Figure 5.shows a top plan view of the em- bodiment shown in Figure 4; Figure 6 shows a bottom view of the embodiment as shown in Figure 4 Figure 7 shows a ,logitudinal cross-sec tional view of the device as shown in Figure 4; and Figure 8 shows a view of the device as shown in Figure 4 in use.

In Figures 1 to 3, a preferred embodiment of the present invention is illustrated and comprises a bottom plate 1 with a centre hole 2 for the cable A, a plurality of bolts 3 and a slit 4 stretching from the flange periphery to the centre hole 2. The bottom plate 1 as well as a top plate 9 is resilient enough to permit each slit to open for fitting onto the cable A and is for example, made of woven synthetic fibres, plastics or the like. The bolts 3 may be fixed to the plate 1 or fitted through the bolt bores (see, for example, the embodiment shown in Figure 7). The plastics for the plates may comprise any suitable known resilient plastics material, e.g. vinyl polymers such as polyvinylalcohol or polyvinylchloride, polypropylene, or the like. The woven synthetic fibre for the flanges may comprise nylon, polyester, polypropylene, fluoro polymer or the like.

A resilient cylinder 5 has an outer diameter which is the same as or slightly smaller than the inner diameter of the cable conduit B and is capable of being easily inserted into the cable protecting conduit (cable pipe) B. This cylinder 5 is made of resilient material such as synthetic rubber and is provided with a plurality of ring-like protuberances 6 circumferentially of the cylinder. The cylinder 5 further comprises a through hole complementing the cable (cable hole 18), at least one (preferably one for smaller cylinders) slit 7 formed and arranged to correspond to the slit 4 in the plate 1 and a number of bolt bores 12 stretching throughout the cylinder body from the bottom to the top end and corresponding to the bolt bores of the plate.

The material for the resilient cylinder 5 may comprise rubber, synthetic rubber or elastic synthetic polymers. The synthetic rubber may further comprise, e.g. a polymer of isoprene or its derivates, neoprene rubber, neoprene-butadiene rubber, silicon rubber, fluoroethene rubber, copolymers of vinyl acetate and vinyl chloride or the like.

The top plate 9 is to sandwich the cylinder in between itself and the bottom plate 1. The plate 9 has a cable hole 10, sleeves 11, bolt bores 12, corresponding to the bolt bores 8, and a slit 13 corresponding to the slits 4 and 7 of the bottom plate and the cylinder respectively. The pair of plates are bolted together using nuts 14. The long sleeves will eliminate the eventual difficulty of screwing up the nuts when the cylinder is placed a distance into the conduit. The number of the slits 4, 7 and 13 assigned to each plate or cylinder may be more than one in relation to the cylinder diameter; however, one slit is preferable for a relatively small diameter of the cable or conduit.

Usually, a pair of plates 1, 9 are used to make the resilient cylinder 5 expand radially and tangentially under the axial compression effected by bolting (without these plates, the bolt heads and nuts would bite into the cylinder body and the desired compression would not result).

A lubricating substance 16 such as lubricating oil is applied between the cable A and the inner surface of the end of the conduit cable before the cylinder is fitted onto the cable A. This lubricating substance 16 may be applied either onto the cable or the inner surface of the cylinder 5. The lubricating substance enables the cable A to slide relatively to the cylinder 5 with very little friction and is preferably a viscous, non-volatile and waterproof lubricant to avoid it flowing out and becoming used up and for retaining a tight sealing. Such a lubricating substance may comprise liquid lubricant such as mineral lubricating oil, silicon oil, a mixture of mineral and silicon oils or the like.

A preferred method of use of the sealing device above described comprises following steps: The lubricating substance 16 is applied to the cable at the pertinent portion. A cylinder 5 sandwiched in between a pair of plates 1, 9 is preliminarily assembled with the bolts 3 and nuts 14 which are slightly screwed up for assembly. In this assembly, each slit 4, 7, 13 of the bottom plate, cylinder and top plate are aligned. A washer 15 is preferably used under each nut. This assembly is fitted onto the cable A bypassing the cable through the slits 4, 7, 13 whereby the bottom plate is arranged adjacent the cable conduit. Then the assembly is pushed into the cable conduit B until the top plate 9 is completely inserted into the conduit end. Finally, the nuts 14 are tightly screwed up, i.e. the resilient cylinder 5 is axially compressed and expanded radially outwards and inwards, and also tangentially, thereby effecting a tight sealing.

The tangential expansion effects a tight sealing of the slit of the cylinder.

The ring-like protuberances 6 of the cylinder effect a tight securing of the cylinder 5 to the inner surface of the cable conduit B and the water tight sealing device remains firmly secured within the end of the conduit.

A further preferred embodiment of the present invention is illustrated in Figures 4 to 8. This embodiment comprises a thin hollow elastic cylinder 205 and a top plate 209 having an essentially larger outer diameter than the inner diameter of the cable conduit B. The bolt head 217 of the bolt 203 is flat as shown in Figure 6, and the bolts 203 are inserted through the bolt bores in the plates 201, 209 and the cylinder 205. Each slit is preferably arranged so that no continuous slit is formed as shown in Figure 4. The cross-sections of the slits 204, 207, 213 preferably exhibit curved gear-like or step-like engaging profiles, e.g. both sides of the slits engage together like a gear. Such slit profiles and slit arrangements have a better sealing effect on the thin cylinder. The outer diimeter of the bottom plate 201 is slightly smaller than the inner diameter of the conduit B, and the inner diameter of the same plate 201 is slightly larger than cable diameter B, which enables an easier insertion of the device and frictionless sliding of the cable relative to the plate 201.

The plates 201, 209 may be doubled. The top plate 209 has an essentially larger outer diameter than the inner diameter of the cable conduit B, thus enabling a more positive location in the cable conduit end mouth D and a more convenient screwing up of the nuts 214. In this case each washer may be a usual flat washer, or this may be sometimes eliminated when a flanged nut is applied thereto provided that the outer surface of the top plate 209 is located out of the conduit mouth D. Preferably, the outer rim end of the top plate 209 has a sloped cross-section corresponding to the profile of the conduit mouth D to the cable pit C as shown in Figure 8.

Accordingly, the above described embodiments provide the following advantages for the liquid or water tight-sealing of the cable conduit end: 1. The sealing device is tightly secured to the conduit inner face thus not effecting falloff by the vibration or quakes from the ground.

2. A tight seal can be achieved.

3. The plates consist of resilient material such as plastics, woven synthetic fibre and the like thus eliminate the likelihood of electronic troubles even if the plates contact the cable.

4. The slits provided in the cylinder and plates permit the device to be fitted onto the cable without difficulty, but however, while achieving a seal.

5. The telephone cable which may be subjected to several thousand of contractions and expansions per day (cf. difference: Imm--l0mm) may slide forwards and backwards even with a watertight sealing. This is enabled by the lubricating substance.

6. The ring-like protuberances circumferential of the cylinder make possible a firm sealing and securing to the conduit as well as avoiding water leaking in even with a slight looseness in comparison to spiral protuberances.

Claims

WHAT WE CLAIM IS

1. A method of liquid tight sealing the ends of cable conduits, comprising fitting onto the cable a resilient cylinder sandwiched between plates with a lubricating substance applied between the cable and cylinder, inserting the resilient cylinder into the end of the conduit and thereafter bolting together the plates so as to compress the resilient cylinder axially and expand the cylinder radially to engage the cylindrical surface with the inner surface of the conduit to retain the cylinder therein.

2. A method as claimed in Claim 1, wherein the resilient cylinder comprises rubber, synthetic rubber or elastic synthetic polymers.

3. A method as claimed in Claim 1 or 2, wherein the lubricating substance is waterproof.

4. A method as claimed in Claim 1, 2 or 3 wherein the lubricating substance comprises mineral oil, silicon oil or a mixture thereof.

5. A method as claimed in any one of Claims 1 to 4, wherein the resilient cylinder has a plurality of ring-like protuberances around its circumference.

6. A method as claimed in any one of Claims 1 to 5, wherein the resilient cylinder comprises at least one slit extending in the axial direction, the bolting together of the plates also causing tangential expansion to close the slit.

7. A sealing device for liquid tight sealing of the ends of cable conduits comprising a resilient cylinder and two apertured plates for fitting on to the cable, means for lubricating the interface between cable and device and means for bolting the two plates together to axially compress the cylinder and thus cause radial expansion thereof.

8. A device as claimed in Claim 7, wherein the resilient cylinder and the plates are provided with a through hole to receive a cable and at least one longitudinal slit.

9. A device as claimed in Claim 8, wherein bolts are arranged in bolt bores through the cylinder body and plates and secured by nuts.

10. A device as claimed in any one of Claims 7 to 9, wherein the resilient cylinder comprises rubber, synthetic rubber or elastic synthetic polymers.

11. A device as claimed in any one of Claims 7 to 10, wherein the cylinder has a plurality of ring-like protuberances around its circumference.

12. A device as claimed in Claim 8 or any claims dependent directly or indirectly therefrom, wherein the plates are resilient enough to permit the slits to open.

13. A device as claimed in any one of Claims 7 to 12, wherein the plates comprise resilient plastics or woven synthetic fibres.

14. A device as claimed in any one of Claims 7 to 13, wherein the plates have an outer diameter not larger than the inner diameter of the intended cable conduit and an inner diameter not smaller than the intended cable diameter.

15. A device as claimed in any one of Claims 7 to 14, wherein one of the plates has an essentially larger outer diameter than the inner diameter of the intended cable conduit.

16. A device as claimed in Claim 14 wherein one of the plates is of frusto conical shape.

17. A device as claimed in Claim 8 or any claim dependant directly or indirectly therefrom, wherein the cylinder and the plates are so assembled that their slits do not form continuous slit.

18. A device as claimed in Claim 8 or any claim dependant directly or indirectly therefrom, wherein the slits of the cylinder and the plates comprise either a curved or step-like cross-section.

19. A method for liquid tight sealing of the ends of underground cable conduits substantially as described herein with refer- ence to the drawings.

20. A device for liquid tight sealing of the ends of underground cable conduits substantially as described herein with reference to the drawings.