Electricity: conductors and insulators – Boxes and housings
Reexamination Certificate
2001-10-24
2004-09-28
Reichard, Dean (Department: 2831)
Electricity: conductors and insulators
Boxes and housings
C174S017070, C174S053000, C220S003200, C220S004020
Reexamination Certificate
active
06797878
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to a closure casing, and particularly to a closure casing for enclosing one or more elongate objects such as pipes or cables, which latter term will be understood hereinafter to include both electrically conductive cables and optical cables comprising bundles of optical fibres.
BACKGROUND OF THE INVENTION
Optical fibres are increasingly used in telecommunications systems and a number of techniques have been developed for joining such fibres at particular points within a communications network. Likewise, electrically conductive cables or wires have to be joined at certain places within the network and at all such junctions closure casings are required in order both to support the connection and to provide protection against environmental agencies such as moisture and dust.
Optical fibres may be joined in a number of ways, utilizing techniques such as splicing or devices such as couplers or splitters. A common feature of all such connections, however, is the requirement for a closure casing which has means for allowing ingress of one or a plurality of cables or bundles of fibres at one end and for egress of one or more cables or bundles of fibres at the other. Such closure casings also find particularly utility where it is necessary to install equipment at an intermediate point along a transmission line. Such equipment may, for example, include repeaters, amplifiers, boosters, attenuators or other such equipment (which equipment is mentioned by way of example and is not intended to be an exhaustive list nor to prejudice the generality of the invention) but whatever equipment the closure casing encloses the common features nevertheless remain that the casing must be capable of being sealed against environmental agencies and have sufficient strength and rigidity to resist external forces and protect the, sometimes delicate, components enclosed therein. Such closure casings in use may be buried underground, or housed in cabinets or other locations in the network.
Although such closure casings must be capable of sealing securely against environmental agents it is very often necessary to gain access to the interior of the casing (so-called “re-entry” requirement) in order to make changes to the network or for maintenance purposes in the event of a failure or breakdown. This re-entry requirement means that a closure casing has to be fastened with releasable fasteners of one form or another and cannot be permanently secured such as by adhesive or welding of the components unless it is acceptable for the casing to be disposed of, upon re-entry, and replaced with a fresh casing. Economically, in view of the complexity of the structure, this is usually not viable.
The present invention seeks to provide a closure casing having releasable fasteners for securing the casing parts in the closed condition, and to a fastener for such a closure, which is releasable quickly and easily to allow an operator access to the interior of the closure casing.
One way in which this has been done in the prior art, is to provide the casing with a surrounding ring or clamp which is held in its closure position by an overcentre clamp or toggle latch. WO96/33922 illustrates such a casing. Closure casings in which co-operating parts are held together by toggle clamps are also shown in EP 0 546 267 which describes a clamping closure for closing a cable sleeve having a clamping claw engageable over a flange at the rim of the closure, and U.S. Pat. No. 4,558,174 which describes a closure for a cable splice having mating covers held closed by a continuous wire latch support frame having a plurality of latching fingers which can snap past a centered bistable position into locking engagement with an aligned seat along the closure. A disadvantage with such structures lies in the relatively complex shape of the outside of the closure casing resulting from the presence of the over-centre clamps which makes the casing difficult to handle and requires extra space for it to be housed. Independent over-centre clamps (also known as toggle clamp) are, of course, known as such. One example is described in U.S. Pat. No. 4,367,569, in which it is referred to as a cam locking pin. This has a pivoted pawl at one end, which can be turned to a first position allowing it to be passed through aligned openings in two components to be held together, and a second position in which it resists removal of the pin from the openings. At its opposite end the pin has aligned transverse lugs engageable by a force-applying tool having a pair of hooks removably engageable with the lugs and having respective wedging portions by which tension can be applied to the pin to hold the components together. Disadvantages of this device include the requirement for manual dexterity in manipulating the pivoted pawl, and the fact that this and its associated pivot pin increase the number of components parts of the device and therefor the cost of construction and assembly, as well as the risk of malfunction due to components being out of tolerance.
As used herein the term “toggle clamp” will be understood to relate to a mechanism comprising two parts pivotally engaged or engageable with respect to one another, one of which comprises a tension member and the other of which comprises an operating member or lever. The axis about which the two parts of the clamp are turnable with respect to one another is spaced from an effective point of contact between the operating member or lever and a part of the closure which it engages in use, the arrangement being such that in turning about the pivot axis between the two clamp members from a release position to a clamped position the line of action through the contact point with the closure member is displaced transversely of the line of action between the pivotable connection between the two clamp members and the contact point of the tension member with the other closure member, passing through a “centre” position in which the pivot axis and the said two lines of action are all aligned, at which point the tension applied to the tension member is at its greatest. In the closure position, therefore, the tension applied to the tension member holds the operating lever in its closed position.
The resilience in a toggle clamp mechanism is usually provided by making the tension member of such a material and shape that it can be stressed upon the application of a tensile force between each end or by the provision of a separate spring of the toggle clamp mechanism acting between the tension member and the operating member or lever such that the spring is compressed as the operating lever moves towards its point of maximum compression as the two lines of action are aligned.
SUMMARY OF THE INVENTION
U.S. Pat. No. 4,727,629 discloses a fastener for removably clamping the edges of two panels, each having a hole therethrough. The fastener includes a hinge pin, about which the fastener body pivots.
FR 2,199,363 discloses a toggle clamp for clamping a plate to a support or to another plate. There is no suggestion to use this clamp for closure casings.
GB 599,354 discloses a pin for temporarily securing together sheet metal plates. The pin proper has two legs which can be forced together by a pivotable body member to permit insertion of the pin in holes. The legs can move apart to clamp the plates together.
U.S. Pat. No. 5,524,672 discloses a pipe thread protector having a toroidal body of elastomer with a bore to accept a pipe end and a metal band and a toggle clamp arrangement extending around its periphery.
According to one aspect the present invention provides a closure casing having two co-operating closure members comprising half-shell structures having cable entry ports and defining an enclosed space between them when in a juxtaposed closure position, the closure being provided with holding means for holding the closure members together in the closure position characterised in that the holding means comprises at least one over-centre or toggle clamp. mechanism one part of
Estrada Angel R.
Myers Bigel & Sibley & Sajovec
Reichard Dean
Tyco Electronics Raychem NV
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