Electricity: conductors and insulators – Conduits – cables or conductors – Combined
Patent
1992-12-16
1994-09-13
Nimmo, Morris H.
Electricity: conductors and insulators
Conduits, cables or conductors
Combined
29868, 156 49, 174 88R, 174DIG8, H02G 1508
Patent
active
053470893
DESCRIPTION:
BRIEF SUMMARY
This invention relates to dimensionally recoverable articles and especially to the use of such articles for the insulation and/or protection of elongate objects such as cable harnesses.
Dimensionally recoverable articles, especially heat-shrinkable articles, are now widely used in many areas where insulation, sealing and encapsulation are required. Usually these articles recover, on heating, towards an original shape from which they have previously been deformed, but the term "heat-recoverable", as used herein, also includes an article which, on heating, adopts a new configuration, even if it has not been previously deformed.
In their most common form, such articles comprise a heat-shrinkable sleeve made from a polymeric material exhibiting the property of elastic or plastic memory as described, for example, in U.S. Pat. Nos. 2,027,962; 3,086,242 and 3,957,372. As is made clear in, for example U.S. Pat. 2,027,962, the original dimensionally heat-stable form may be a transient form in a continuous process in which, for example, an extruded tube is expanded, whilst hot, to a dimensionally heat-unstable form but, in other applications, a preformed dimensionally heat stable article is deformed to a dimensionally heat unstable form in a separate stage.
In other articles, as described, for example, in British Patent 1,440,524, an elastomeric member such as an outer tubular member is held in a stretched state by a second member, such as an inner tubular member, which, upon heating, weakens and thus allows the elastomeric member to recover.
In certain circumstances it is necessary to enclose a branch in an electrical cable, in which case a clip may be employed to bifurcate the dimensionally recoverable article into two (or more) outlets for the cable, a number of such clips being described in UK patent specification No. 1,604,981. However, most clip arrangements that have been proposed are intended for use with telecommunications cables. The present invention, however, is intended to be employed for enclosing branch-offs in smaller cables such as an electrical wiring harness, especially one that is intended for use in a high temperature sealed environment, e.g. for military use. In contrast with branch-offs employed for telecommunications, these branch-offs are often subjected to prolonged periods in use during which the temperature rises above the recovery temperature of the sleeve so that the clip is therefore again subjected to the "milking off" forces, sometimes on a continual basis and often in the presence of vibration.
According to one aspect, the present invention provides an arrangement for enclosing a branch-off between a pair of elongate bodies, which comprises a dimensionally recoverable sleeve which can surround the branch-off, and one or more clips which can be positioned about opposed walls of the sleeve to divide the sleeve into channels for the bodies, the or each clip being of unitary form and having a pair of legs that are splayed outwardly to facilitate positioning of the clip over the sleeve walls, the or each clip being deformable so that the legs can be forced towards each other after the clip has been positioned on the sleeve walls but sufficiently rigid, at least in is deformed state, to resist opening out of the legs under the recovery forces of the sleeve.
The arrangement according to the invention has the advantage that it is relatively simple and easy to install even where small articles are to be enclosed, e.g. branch-offs having dimensions in the order of a few centimeters or less. In addition, the arrangement can be used to form an effective seal, at least in the preferred forms of arrangement, when the cable or harness is subjected to elevated temperatures as may be found in an automotive or military environment.
The clip is preferably in a generally sheet-like form, each leg having a major surface that faces the other leg, and most preferably has been formed by stamping a shape out of sheet material and folding it into the appropriate shape. This form of clip may easily be pushed
REFERENCES:
patent: 4246687 (1981-01-01), Nolf
patent: 4400579 (1983-08-01), Nolf
patent: 4420654 (1983-12-01), Muller
patent: 4625073 (1986-11-01), Breesch et al.
patent: 4648924 (1987-03-01), Nolf
patent: 4954670 (1990-09-01), Jensen et al.
Barrat Alan
Miles Graham
Burkard Herbert G.
Nimmo Morris H.
Novack Sheri M.
Raychem Limited
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