EP0795221A1

EP0795221A1 - Seal

Info

Publication number: EP0795221A1
Application number: EP95938499A
Authority: EP
Inventors: Luc Breyssem
Original assignee: Raychem NV SA
Current assignee: Commscope Connectivity Belgium BVBA
Priority date: 1994-11-30
Filing date: 1995-11-30
Publication date: 1997-09-17
Also published as: MX9703943A; WO1996017423A1; GB9424137D0; AU3986995A; BR9509931A; JPH10510137A; CA2206323A1

Abstract

An elongate compressible seal (1) in which, in use, two ends (3) are joined together by means of at least one connection pin (5) located in, and extending between, at least one opening in each end (3), wherein the or each connection pin (5) is hollow and compressible and the seal (1) is therefore compressible at the join between the two ends (3).

Description

Seal

The present invention relates to a seal, and in particular to a ring seal The seal may generally be used to seal between any two surfaces, but it has particular utility in electrical or telecommunications cable splice closures

United States Patent No 4558174 (AT&T Bell Laboratories) discloses a closure for a cable splice which has two mating covers and two end plate assemblies A peripheral channel in each end plate is filled with a circumferential gasket which seals between the periphery of each end plate and the surrounding covers The ends of each circumferential gasket are connected together This is accomplished by forming each circumferential gasket with a pair of longitudinally extending passageways At the junction of the ends of the gasket, pins are positioned in the passageways such that they extend from one end The other end is brought into juxtaposition with the one end and the extending pins are caused to be positioned in the passageways of the other end

Ring seals for cable splice closures, which comprise a single elastomeπc tube, the ends of which are joined together by means of a solid connection pin, are also known

An object of the present invention is to provide an elongate compressible seal in which two ends can be joined together firmly, yet substantially without detriment to the compressibility of the seal at the join Another object of the invention is to provide an improved seal which is compressible, preferably substantially uniformly compressible, along substantially its entire length Where the seal is, in use, a nng seal, the seal is consequently preferably compressible around substantially the entire nng

According to the invention, there is provided an elongate compressible seal in which, in use, two ends are joined together by means of at least one connection pin located in, and extending between, at least one opening in each end, wherein the or each connection pin is hollow and compressible and the seal is therefore compressible at the join between the two ends Preferably, the seal is hollow, i e hollow in addition to being hollow at each end by virtue of the or each opening

The invention has the advantage that, because the connection pin is hollow and compressible, the seal is compressible at the join between the two ends This is in contrast with the known tubular ring seals mentioned above, in which the ends are joined together by means of a solid connection pin and consequently the seal is substantially incompressible at the join, or at least is significantly less compressible at the join than around the remainder of the seal This generally means that with these known ring seals, there is a region of the seal which has significantly poorer sealing characteristics than the remainder of the seal In addition, with these known ring seals it is generally necessary, when installing the cable splice closure, to orientate the ring seal such that the join (which has poor sealing characteristics) is not located at the so-called triple point (i e the point of intersection of the ring seal and the longitudinal seal of the splice closure casing) This is because the triple point is generally the location which needs the greatest degree of reliability from the seals if the environmental sealing of the splice closure is to be maintained The seal of the invention can advantageously be used as a circumferential seal and/or a longitudinal seal in a cable splice closure in which such seals meet at a triple point

Preferably, the seal according to the invention is resiliently compressible and/or the or each connection pin is resiliently compressible, and advantageously the seal is therefore resiliently compressible at the join between the two ends This normally has the advantage of making the seal particularly reliable, since when the seal is compressed between two surfaces, for example, its resilience normally causes it to press against the surfaces

The seal according to the invention may advantageously be substantially uniformly compressible, in use, along substantially its entire length Even more advantageously, the seal may, along substantially its entire length, be substantially uniformly resilient to compression, in use The or each join in the seal, when containing the hollow compressible connection pιn(s), therefore preferably has substantially the same, or at least approximately the same, degree of resilient compressibility as does the remainder of the seal In some embodiments of the invention, this may advantageously be achieved by using one or more hollow compressible connection pins which have very little resilience upon being compressed, e g substantially negligible resilience compared to the resilience exhibited by the remainder of the seal

The outer diameter of the connection pιn(s) is preferably greater than the diameter of the openings in the ends of the seal in which the connection pin is, or the connection pins are, located This can have the advantage of enabling a tight grip to be formed between the connection pιn(s) and the ends of the seal

The connection pin is, or pins are, preferably an interference fit in the openings in the ends of the seal Additionally or alternatively, however, the pιn(s) and/or openings may be profiled to interlock with each other The seal is preferably a ring seal, e g an 0-rιng seal, and preferably has a substantially annular shape in use The seal may, for example, extend around an end block of a cable splice closure, to form a seal between the end block and the casing of the closure which surrounds the end block The two ends in the seal which are joined together by means of the or each connection pin are preferably opposite ends of the same discrete elongate article The seal is therefore preferably an elongate seal the two ends of which are joined together to form a closed loop Additionally or alternatively, however, the two ends in the seal which are joined together by means of at least one connection pin according to the invention may be the ends of different discrete elongate articles The seal according to the invention may therefore comprise two or more discrete seals which are joined end-to-end by means of at least one connection pin according to the invention The seal may, for example, be a linear seal, e g a longitudinal seal of a cable splice closure, and/or the seal may be a ring seal formed from two or more discrete seals joined together

It was mentioned above that the seal and the connection pιn(s) are hollow The seal and the connection pin may advantageously be hollow by virtue of any suitable internal structure The seal itself and the connection pιn(s) may, in some embodiments, have different types of internal structure, but preferably they have substantially the same type of internal structure The seal and/or the connection pιn(s) may, for example, comprise polymeric foam, either closed-cell foam or open-cell foam In most preferred embodiments however, the seal and/or the connection pιn(s) are not formed from polymeric foam

The seal and/or the or each connection pin may advantageously be tubular When the or each connection pin is tubular it may, for example, be closed at one or both ends, but preferably it is open at both ends The connection pιn(s) may, in some embodiments, advantageously have a longitudinal slit In this way the or each pin can often have very little resilience to compression (the advantage of which was explained above) and/or the or each pin can grip the ends of the seal firmly The longitudinal edges of the slit may, for example, overlap

The seal of the invention may advantageously have at least one cavity extending along substantially its entire length, and the openings in which, in use, the or each connection pin is located are preferably ends of the or each cavity As mentioned above, the seal may, for example, be tubular Preferably, the cross-sectional diameter of the or each cavity is substantially uniform along substantially the entire length of the seal In certain preferred embodiments, the seal may be formed from sealing material, and/or it may have sealing material as at least part of an external surface thereof A preferred sealing material is gel The gel may, for example, comprise sihcone gel, urea gel, urethane gel, thermoplastic gel, or any suitable gel or gelloid sealing matenal Preferred gels compnse an oil - extended polymer composition Preferably the gel has a hardness at room temperature as determined using a Stevens-Volland Texture Analyser of greater than 45g, particularly greater than 50g, especially greater than 55g, e g between 55g and 60g It preferably has a stress-relaxation of less than 12%, particularly less than 10% and especially less than 8% Tensile modulus at 100% strain is preferably at least 1 8 MPa more preferably at least 2 2 MPa In general compression set is preferably less than 35%, especially less than 25% Preferably, the gel has a cone penetration as measured by ASTM D217 of at least 50 (10"¹mm), more preferably at least 100 (10"¹mm), even more preferably at least 200 (10" ¹mm) and preferably no greater than 400 (10^_1mm), especially no greater than 350 (10^_1mm) The polymer composition of the gel may for example comprise an elastomer, or a block copoiymer having relatively hard blocks and relatively elastomeπc blocks Examples of such copolymers include styrene-diene block copolymers, for example styrene-butadiene or styrene-isoprene diblock or triblock copolymers, or styrene-ethylene-butylene-styrene tπblock copolymers as disclosed in international patent publication number WO88/00603 Preferably, however, the polymer composition comprises one or more styrene-ethylene-propyleπe-styrene block copolymers, for example as sold under the Trade Mark 'Septon' by Kuraray of Japan The extender liquids employed in the gel preferably comprise oils The oils may be hydrocarbon oils, for example paraffinic or naphthenic oils, synthectic oils for example polybutene or polypropene oils, and mixtures thereof The preferred oils are mixtures of non- aromatic paraffins and naphthenic hydrocarbon oils The gel may contain additives, e g such as moisture scavengers (eg Benzoyl chloride), antioxidants, pigments and fungicides

The seal is preferably formed, at least in part, from elastomeπc material For example, the seal may be formed from natural or synthetic rubber, or a rubber-like plastics material Neoprene is an example of a preferred material

As stated above, the seal according to the invention has particular utility in an electrical or telecommunications cable splice closure Preferably, therefore, the seal compnses part of a cable splice closure The seal may, for example, comprise a ring seal which, in use, extends around an end block of the cable splice closure, e g between the end block and an outer casing of the closure The splice closure may, for example, have only one such end block, but preferably it has two such end blocks, one at each end of the casing According to a second aspect of the invention, there is provided a cable splice closure which includes one or more seals according to the invention Any or all of the preferred features of the seal according to the first aspect of the invention may advantageously be present in the seal(s) included in the cable splice closure according to the second aspect of the invention

The invention will now be described, by way of example, with reference to the accompanying drawings, of which

Figure 1 shows a join region of a seal according to the invention, and details of a preferred form of connection pin for forming the join, and

Figure 2 shows a join region of a similar seal according to the invention, and details of another preferred form of connection pin for forming the

Figure 1 shows a tubular seal 1 , in which two ends 3 are about to be joined together by means of a tubular connection pin 5 The connection pin 5 comprises an open-ended tube which has been inserted into one of the open ends 3 in the tubular seal 1 To join together the two ends 3 of the seal 1 to form a closed ring seal, the tubular connection pin may be inserted into the other open end 3 of the seal Preferably, the outer diameter of the connection pin 5 is greater than the diameter of the openings in the ends 3 of the seal 1 , causing the seal 1 to grip the connection pin 5 firmly and thereby form a firm join

Figure 2 shows a tubular seal 1 similar to that shown in Figure 1 , with a modified form of hollow connection pin 7 This connection pin 7, although tubular (at least in use), has a longitudinal slit 9, the longitudinal edges of which overlap This type of connection pin 7 can often be more compressible (i e it can often be compressed more easily than that shown in Figure 1) and/or it can often have an increased grip on the ends of the seal 1 In this embodiment too, the outer diameter of the connection pin 7 is preferably greater than the diameter of the openings in the ends 3 in the seal 1

Claims

1. An elongate compressible seal in which, in use, two ends are joined together by means of at least one connection pin located in, and extending between, at least one opening in each end, wherein the or each connection pin is hollow and compressible and the seal is therefore compressible at the join between the two ends

2 A seal according to claim 1 , which is hollow

3. A seal according to claim 1 or claim 2, which is resiliently compressible and/or in which the or each connection pin is resiliently compressible, and the seal is therefore resiliently compressible at the join between the two ends

4 A seal according to any preceding claim which, in use, is a ring seal

5 A seal according to claim 4, in which the two ends are opposite ends of the same discrete elongate article

6 A seal according to any preceding claim, in which the or each connection pin is tubular

7 A seal according to claim 6, in which the or each connection pin has a longitudinal slit

8 A seal according to claim 7, in which the longitudinal edges of the slit overlap

9 A seal according to any preceding claim, which has at least one cavity extending along substantially its entire length, and the openings in which, in use, the or each connection pin is located are ends of the or each cavity

10 A seal according to any preceding claim, which is tubular.

11 A seal according to any preceding claim, which has sealing material as at least part of an external surface thereof

12 A seal according to claim 11 , in which the sealing material comprises gel

13. A seal according to any preceding claim which is formed, at least in part, from elastomeric material.

14. A seal according to any preceding claim, which comprises part of a cable splice closure.

15. A seal according to claim 14, in which the seal comprises a ring seal which, in use, extends around an end block of the cable splice closure.

16. A cable splice closure which includes one or more seals according to any preceding claim.