Electricity: conductors and insulators – Conduits – cables or conductors – Insulated
Patent
1995-03-29
1997-02-18
Kincaid, Kristine L.
Electricity: conductors and insulators
Conduits, cables or conductors
Insulated
174124GC, 174122R, H01B 718
Patent
active
056043317
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to an anti-fire sheath intended mainly for providing cabling with mechanical protection and with thermal protection in the event of a fire, in particular for use in the fields of aviation, space, and industry. The invention also relates to a method of making the sheath.
In certain conditions of use, cables or cable harnesses providing electrical connections within mechanical or electronic units are liable to be subjected for a greater or lesser length of time to high temperatures exceeding those specified by the manufacturers of the products concerned. In most cases, that causes the connections to be interrupted which can lead directly or indirectly to the equipment concerned being destroyed. In space applications, the loss of one essential function can abort the entire mission with consequent financial loss, and in the field of aviation, the failure of essential equipment such as emergency lighting, for example, can be a direct cause of loss of human life in the event of an aircraft crashing.
At present, the techniques used for providing cables with thermal protection are essentially of three kinds:
for aviation applications, such temperature protection is provided by placing the various cable paths in cold zones that are specially designed to withstand such high temperatures. Such a solution, in addition to being very expensive since it requires complex cooling systems, is not really effective as has been demonstrated by the latest analyses of recent aircraft accidents. In addition, in the engine environment of aircraft, the cables passing through zones that are at risk are special cables already having a fireproof rating, that are very expensive, and that have high mass and bulk per unit length;
in space applications, the ability to withstand temperature is provided during final assembly of the equipment by covering the cables and cable harnesses in a flexible spiral type protective covering based on a "Jehier" type material or in a more rigid protective covering based on silica or glass fibers, such as "Reprobat". However, those solutions require considerable time to be implemented and they are particularly expensive and penalizing as to weight. In addition, the first kind of protective covering is effective up to about 200.degree. C. only, while the second suffers from a baking effect caused by the capacity of the fibers to absorb heat. In addition, protective coverings based on silica or glass fibers require special precautions in use given their toxicity; and
in industrial applications, it is common practice to use special cables that have a fireproof rating, in particular cables based on PTFE and having operating temperatures that may be as high as 300.degree. C. to 400.degree. C. However since such high quality cables are very expensive, there can be no question of making bundles of cables using that technique.
None of the above solutions is entirely satisfactory, since they do not enable the needs of users to be optimized with respect to mass, cost, maximum temperature, and time required for implementation.
Thus, a search for novel solutions has been undertaken by the French company Aerospatiale, starting from thermal screens based on materials having low transmissivity in the infrared and commonly used in firefighting. For example, such screens are sold by the company Ariegeoise de Bonneterie, of Montferrier (09), France, under the name MONSEGUR. That search has led to French patent application No. FR 2 666 048 which sets out to protect a material based on a superpostion of MONSEGUR fabric sheets and covered on each face with a layer of silicone. Unfortunately that novel thermal protection is still not satisfactory since, as in the prior art, it can only be implemented on final assembly of the equipment. Further, it remains heavy, expensive, and difficult to implement, and by its very structure it is not adapted to protecting a single cable having a diameter of a few millimeters. It should also be observed that given the significant stiffness of
REFERENCES:
patent: Re30414 (1980-10-01), Kinoshita
patent: 3900701 (1975-08-01), Bayles et al.
patent: 4051324 (1977-09-01), Anderson et al.
patent: 4312260 (1982-01-01), Morieras
patent: 5075514 (1991-12-01), Hurd
patent: 5227586 (1993-07-01), Beauchamp
Gaillard Guy
Maillard Charles
Matarin Didier
Peltot Michel
Kincaid Kristine L.
Labinal
Machtinger Marc D.
Societe Europeenne de Propulsion
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