Electricity: conductors and insulators – Insulators – Through wall or plate
Patent
1985-08-29
1987-10-27
Askin, Laramie E.
Electricity: conductors and insulators
Insulators
Through wall or plate
174156, 248 56, 277 70, 277193, 277199, 277227, F16L 502, H01B 1730
Patent
active
047031360
DESCRIPTION:
BRIEF SUMMARY
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a National Phase application of PCT/DE No. 85/00093 filed Mar. 28, 1985 and based under the International Convention on German National application No. P 34 12 400.4 filed Apr. 3, 1984.
FIELD OF THE INVENTION
The invention relates to a sealing body for a feedthrough for at least one conducting member, particularly an electrical cable, traversing a wall opening, whereby an elastic sealing body fills at least partially a clearance between the conducting member and the wall of the opening, creates a receiving space for the conductor corresponding to the cross section thereof and, due to compression into the wall opening, also creates a seal against tne conductor and against the wall of the opening.
BACKGROUND OF THE INVENTION
Known feedthroughs and sealing bodies of this kind function to provide a fire-protecting seal whereby a path for the conductor, separated into fire-resistant segments by the wall, are sealed with respect to one another in a fire-resistant manner. In addition to maxium fire retardation, the feedthroughs and the sealing bodies should have the best possible sealing properties against water, gas and smoke. The known sealing bodies are made of synthetic rubber, such as neoprene or chloroprene, to which, for the desired fire-resistance duration, fire retardant and expanding materials and the like are added. The admixture of these substances to the rubber composition, however, reduces considerably the technical value of the rubber mixture. For example, hardening occurs in the rubber with the addition of relatively small quantities of additives. When the quantity of the additives corresponds to the desired duration of fire-retardant properties, the rubber body can be hardened so much that it may have insufficient elasticity and cannot provide a satisfactory seal against water, gas or smoke. It is also necessary to provide an elastic rubber which is as soft as possible so that the sealing body will adhere snugly to the conductor and the wall of the opening when pressed into the opening. Besides, these rubber mixtures with such additives are expensive, since the admixing process is quite involved. This, in turn, leads to the high cost of such special rubber mixtures. Finally, such sealing bodies, which usually are dimensioned to be quite thick, require extended vulcanization times, so that the forms in which the sealing bodies are vulcanized remain occupied for long times, thereby also contributing to production costs.
OBJECT OF THE INVENTION
The object of the invention is to provide a sealing body for the purposes described which requires the smallest possible quantity of special rubber mixtures with fire-resistant additives for its production ad which does not lose its sealing properties even when the quantity of the admixed additives is quite high.
SUMMARY OF THE INVENTION
This object of the invention is achieved with a sealing body consisting of two separate parts, each extending essentially transverse to the axis of the opening and which are form-locked together at their junction face. One of these parts is made of an elastic and soft rubber (without the stiffening additives or with very little of the flame-resistant additives) and is formed with the sealing surface pressing against the wall of the opening. The other part is made of a harder rubber from the point of view of elasticity with a larger amount of the flame-resistant additives and engages in a recess of the soft, elastic part, pressing axially against the recess, as well as radially in the circumference of an annular shoulder defining the recess externally. In a preferred embodiment, both parts are made of chloroprene rubber, whereby the soft elastic part has a Shore hardness of a maximum of 55 and the elastically harder or stiffer part has a Shore hardness of at least 60. In addition, the arrangement provides that the elastically harder sealing portion is the part of the sealing body facing the outer surface of the wall, while the elastically softer portion i
REFERENCES:
patent: 2722438 (1955-11-01), Kennison
patent: 2924472 (1960-02-01), Bush
patent: 3076668 (1963-02-01), Famely
patent: 3091795 (1963-06-01), Budwig
patent: 4081879 (1978-04-01), Rubright
patent: 4480843 (1984-11-01), Springer et al.
Askin Laramie E.
Dubno Herbert
Ross Karl F.
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