GB2480375A

GB2480375A - Electrical cable gland with captive cone

Info

Publication number: GB2480375A
Application number: GB201107761A
Authority: GB
Inventors: Nicholas Franz Edward Lackinger
Original assignee: TOLLARD HOLDINGS Ltd
Current assignee: TOLLARD HOLDINGS Ltd
Priority date: 2010-05-13
Filing date: 2011-05-10
Publication date: 2011-11-16
Anticipated expiration: 2031-05-10
Also published as: AU2011202197A1; CN102315617A; SG176373A1; HK1166187A1; KR101651976B1; KR20110125617A; GB201107761D0; CN102315617B; AU2011202197B2; ZA201103348B; GB2480375B

Abstract

A cable gland has a tubular inner body part 4, a tubular outer body part 1 and an armour clamp assembly comprising an armour clamping cone 7 associated with the inner body part and a cooperating armour clamping ring 8 associated with the outer body part. The armour damping cone is held releasably captive relative to the said inner body part to permit a cable gland to be composed of two subassemblies, at least for initial installation purposes, by means of an resilient elastomeric ring 14 encircling an extension 9 to the armour clamping cone. The elastomeric ring cooperates with both the said extension and the inner body part to hold the armour damping cone captive relative to the inner body part but releasable therefrom. The elastomeric ring may be an O-ring which is partially accommodated in a groove 15 in the outer surface of the extension to the armo ur clamping cone. The inner body part of the cable gland may have, at the entry end thereof, an inwardly directed lip 16 for retaining the elastomeric ring within the tubular body in a releasable manner. The ring may be held captive to the outer body part by a further O-ring 17, allowing these parts to be removed together so that the gland can be inspected whilst in use. The armouring may be a braid or metal tape providing protection and/or an electromagnetic shield.

Description

I

ELECTRICAL CABLE GLAND WITH CAPTIVE CONE

FIELD OF THE INVENTION

ThIs Invention relates to electrical cable glands of the type comprIsing an internal armor damp assembly typically composed of an armor clamping cone associated with an inner body part of the cable gland and an armor clamping ring associated with an outer body part of the cable gland.

More particularly, but not exclusively, the Invention relates to an electrical cablegland thatfacilitates atleastpartial removal ofthe outerbodypartto permit Inspection of the armor damp assembly at any required time after installation of the cable gland and without disturbing the armor clamp ftselt This may also enable Inspection of an inner seal acting between an Inner sheath of a cable and the Inner body part of the cable gland.

SUN more particularly, but not exclusively, the Invention relates to electrical cable glands of the type described In British patent no 0B2368201, the contents of which are Incorporated herein by reference.

ftistobenotedthatthetermarmorlnglsusedhereinlnabroadsenseanij Includes a layer In the form of longitudinally extending relatively stiff wires of signIficant thickness between the Inner and outer Insulating sheaths of a cable; armoring In the form of fine, substantially more fiedble, optionally braided, wires; and metal tape. The arn'iorlng may serve one or more functions including, but not limited to, physically protecting or relnfordng the cable; providing an electrically conductive earth; and providing an electromagnetIc shield.

BACKGROUND TO THE INVENTION

In order to provide a twopart construction of a cable gland for the purposes of ease and security of instaflation without either the armor clamping cone or the armor damping ring beThg bose and therefore susceptible to being lost and omitted from the installed assembly, the armor damping cone is held captive r&abve to one part of the cable gland, typic&ly the inner body part of the cable gland, whilst the armor clamping ring is held captive relative to the other part of the cable gland, typically the outer body part of the cable gland.

As described in British patent GB2368201 preventative maintenance of electrical installations is becoming commonplace! In instances in which such maintenance involves inspection of the inner seal of a cable gland this requires that the armor clamping cone be separable from its associated part of the body of the gland for the purposes of inspection without disengaging the armor clamp.

Various constructions have been proposed and used for holding the armor clamping cone captive relative to its associated body part of the gland. In the past, spring clips encircling an extension to the cone of the armor clamp have been used in cooperation with an inwardly directed lip or flange provided on the inner surface of the tubular body part.

British patent number 0B2366201 proposes an interference fit between an inwardly directed ridge provided on the tubular body part and an outwardly directed flange provided on the tubular extension to the armor clamping cone of the armor clamp.

However, neither of these expedients has proved satisfactory in practice as the spring clip does not release adequately easily, when required, and the interference fit requfres extremely close manufacturing tolerances in order to operate effectively.

OBJECT OF THE INVENTION

ft is one object of the invention to provide a cable gland in which the armor damping cone is h&d captive r&ative to an inner body part of the cable gland in a more expeditious manner than heretofore so as to enable a cable gland to have a two subassembly configuration.

It is another object of this invention to provide a cable gland of the above general type which permits inspection of the inner seal and usually also the armor clamp without necessitating the use of loose components at the time of initial installation.

SUMMARY OF THE INVENTION

In accordance with this invention there is provided a cable gland comprising a body including a tubular inner body part and a tubular outer body part and an armor clamp assembly wherein the latter has an armor clamping cone associated with the inner body part and a cooperating armor clamping ring associated with the outer body part, the armor damping cone being held releasably captive relative to the said inner body part to thereby permit a cable gland to be composed of two subassemblies at least for initial installation purposes, the cable gland being characterized in that the armor clamping cone is held releasably captive relative to the said inner body part by means of an elastomeric ring encircling an extension to the armor clamping cone and cooperating with both the said extension and the inner body part to hold the armor clamping cone captive relative to the inner body part but releasable therefrom.

Further features of the invenflon provide for the elastomeric ring to be an O rEng that is preferably partially accommodated in a groove in the outer surface of the extension to the armor clamping cone; for the inner body part of the cable gland to have at the entry end thereof, an inwardly directed Up for retaining the elastomeric ring within the tubular body in a releasable manner; for the cable gland to have a twosubassembly construction with the armor clamping cone being held capUve r&ative to the inner body part and the armor clamping ring being held at least temporarily captive r&ative to the outer body part with the two body parts being movable axially by virtue of cooperating screw threads thereon; and for the cable gland to embody both inner and outer compression seals for seaUng onto the inner and outer sheaths of a cable, The armor clamping ring may be held releasably or temporarily captive relative to the outer body part by any suitable means such as those described in said published British patent number 0B23$8201.

In the case of an inner seal, the seal will generally be accommodated in a bore of the inner body part and will, in use, be compressed axially by the free end of the extension to the armor clamping cone, In order that the invention may be more fully understood, one preferred embodiment thereof will now be described with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings: Figure 1 is an elevation of a cable gland according to the invention with the upper half thereof shown in section; and, Figure 2 is an enlarged view of the central region of the cable gland illustrated in Figure 1.

DETAILED DESCRIPTION WITH REFERENCE TO THE DRAWINGS

In the embodiment of the invention illustrated in the drawings, the invention is applied to a cable gland that is also provided with a so-caDed deluge seal for preventing the ingress of moisture into the interior of the gland where the armor clamp assembly is located. Of course, the invention can also be applied to many other cable glands.

In this particular embodiment of the inventbn the cable gland comprises an outer tubular body part [1] having a free end [2] forming an entry end for a cable [3] and an inner tubular body pad 4] having an externally screw threaded portion [5] in cooperating engagement with an internally screw threaded portion [6] of the outer tubular body.

In the installed condition, the two bodies form an internal cavity housing an armor clamp assembly that includes an armor clamping cone [7] and a cooperating clamping ring [8] that are operatively urged into cooperating relationship by screwing the inner tubular body into the outer tubular body.

The cone has a rearwardly directed tubular extension [9] which, in the installed position, compresses an elastomeric inner compression seal [10] in well established manner. The entry end of the gland has an elastomeric outer compression seal [11] which is independently brought into service by means of a union nut [1 2J screwed onto the entry end of the body.

The armor clamping cone [7] and cooperating clamping ring [8] have cooperating conical clamping surfaces The cone angle of these surfaces is substantiafly conventional [for example, a cone angle of 20 degrees or, in other words, 10 degrees to the axis of the gland] and of self locking type.

These surfaces are adapted to damp the armor wires [13] of a cable between them.

Turnhig now to the r&easable attachment of the armor damping cone [7] to S the inner tubular body part in terms of this invenfion, this is achieved using an endless elastomeric ring that is, in this instance, an Oring [14] of a suitable diameter and crosssectional dimension. The Oring is seated in a groove [15] in the outer surface of the extension [9] towards the end thereof remote from the armor damping cone itsef and the Oring cooperates with the inner surface of the inner tubular body part E4] The armor clamping cone and its extension may be held captive r&ative to the inner tubuar body part simply by virtue of frictional engagement of the Oring with the inner surface of the inner tubular body part. It is, however, preferred that the inner tubular body part have an inwardly directed lip [16] for retaining the elastomeric ring within the tubular body in a releasable manner.

It wifi be understood that with the armor damp assembly operatively engaging the armor wires of a cable, the outer and inner tubular body parts of the cable gland can be disengaged from each other without disturbing the lock between the two conical surfaces and the armor wires and, in the instance of the armor clamping cone, the inner seal can be inspected as may be required by disengaging the extension to the armor clamping cone from the inner body part.

It is to be mentioned that the cooperating clamping ring [8] of the armor clamp assembly is also held releasably captive relative to the outer body part of the gland so that the outer body part can be moved away from the armor clamp to enable it to be inspected for corrosion or for any other purpose. The cooperating clampng ring [8] is also held captive utilizing an elastomeric 0-ring [17] partially accommodated within a groove in the outer surface of the clamping ring.

As indicated above, the invention is embodied in a cable gland havfrig a deluge seal for preventing the ingress of moisture between the inner and outer body parts of the cable gland and this is further described below for

completeness of disclosure.

The external screw threaded portion [5J on the inner tubular body part is of short length and is confined to an inner end region of the inner tubular body part. A smooth outer cyUndrical surface [20] having a diameter slightly less than the minimum diameter of the screw threaded end region extends from said screw threaded end region to a nut formation [21] that is axiaVy external of the outer tubular body part.

The inner surface of the outer tubular body part has an endless O..ring sea [22] accommodated in a circumferential groove [23] adjacent its end that receives the inner tubular body. The Oring seal engages the outer cyllndrical surface of the inner tubular body to totally seal against any ingress of moisture from the outside to the cavity housing the armor damp assembly, and thus to the armor wftes, In order to facilitate assembly of the cable gland, the end of the outer tubular body receiving the inner tubular body has a leadin taper [24] arranged such that an Oring fitting snugly on the outer cylindrical surface of the inner tubular body immediately adjacent the screw threaded end region will automaticafly be squeezed and rolled into the outer tubular member and thereby caused to snap into its operative position in the circumferential groove.

In order to assist in this, the inner tubular body is provided with a shallow groove [25] immediately adjacent the externally screw threaded portion [5] so that the Oring seats itseff partiaUy in that groove. Such a groove typically has a width less than that of the crosssectional diameter of the Oring, and preferably about one half of the crosssectional diameter of the Oring. The

S

internal screw thread in the outer tubular body may extend past the circumferential groove for convenience of manufacture.

R wifi be appreciated that the cable gland, in this embodiment of the s invention, has a two subassembly construction with the clamping cone being h&d captive relative to the inner tubular body and the clamping ring being held captive in the outer tubular body.

It will also be understood that numerous variations may be made to the embodiment of the invention described above without departing from the scope hereof, In particular, the nature of the gland may vary widely and the purpose of holding the armor clamping cone captive relative to the inner body part of the cable gland may be simply to provide a two subassembly construction for installation purposes, In such an instance the feature of enabling inspection of an inner seal becomes irrelevant.

Claims

CLAIMS: 1. A cable gland comprising a body induding a tubular inner body part and a tubular outer body part and an armor damp assembly wherein the latter has an armor damping cone associated with the Inner body part and a cooperating armor damping ring associated with the outer body part, the armor damping cone beIng held releasably captive relative to the said inner body part to thereby permit a cable gland to be composed of two subassemblies at least 1kw initIal installation purposes, the cable gland beIng characterized in that the armor clamping cone Is held reieasably captive relative to the said Inner body part by means of an elastomeric ring encircling an extension to the armor damping cone and cooperating with both the said extension and the inner body part to hold the armor clamping cone captive relative to the inner body part but releasable therefrom.
2. A cable gland as claimed in claim I in which the elastomeric ring is an 0-ring.
3. A cable gland as claimed in claim 2 In which the 0-ring is partially accommodated in a groove In the outer surface of the extension to the armor damping cone.
4. A cable gland as claimed in any one of the preceding claims In which the Inner body part of the cable gland has at the entry end thereof, an Inwardly directed lip for retaining the elastomeric ring within the tubular body in a releasable manner.
5. A cable gland as claimed In any one of the preceding claims In which the cable gland has a two-sub-assembly construction with the armor damping cone being held captive relative to the Inner body part and the armor clamping ring being held at least temporarily captive relative tothe outer body partwlth the two body parts being movable axially by virtue of cooperating screw threads thereon.
6. A cable gland as claimed in any one of the preceding claims in which the cable gland embodies both inner and outer compression seals for sealing onto Inner and outer sheaths of a cable.
7. A cable gland as claimed in claim 6 in which the inner seal Is accommodated in a bore of the inner body part and Is located to be compressed axially by the free end of the extension to the armor clamping cone.
8. A cable gland substantially as hereIn described and exemplified with reference to the accompanying drawings.