Electricity: conductors and insulators – Conduits – cables or conductors – Combined
Reexamination Certificate
1999-11-17
2001-02-06
Kincaid, Kristine (Department: 2831)
Electricity: conductors and insulators
Conduits, cables or conductors
Combined
C174S068300
Reexamination Certificate
active
06184470
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is directed to a seal insert with a rectangular cross-section made of an elastic plastic material for seals between a seal body and a cable sleeve body.
U.S. Pat. No. 5,545,851, which claims priority from the same German Application as EP 0 652 619-B1, discloses a cable sleeve wherein the cable system is arranged circumferentially at the seal body. This seal system comprises a seal channel, which can be reduced in volume, and a seal ring that is inserted into the seat channel. The seal channel is reduced in volume by applying force on a movable channel wall, which movable wall presses the inserted seal ring in a direction offset by 90° relative to the force applied and into the surrounding sleeve wall. In this case, the seal insert is formed entirely of an elastic material and is deformed accordingly and, thus, seals circumferentially. In the deformation of the compact seal material, however, a precise adjusting is necessary in order to achieve clear seal conditions.
EP 0 443 118-B1 discloses a tube seal with a tubular cross-section for sealing in seal channels of cable fittings, wherein a cavity of the tube proceeds in the interior. This serves the purpose of being able to fashion a softer seal. However, this potentially leads to these seal inserts forming an oval and tending to collapse when pressed together. Therefore, pressure against the sealing surfaces cannot be built up. Besides, such circular tube seals only form a seal which lies in a narrow region along a generated line of the seal insert or, respectively, of a seating line of the seal surface.
SUMMARY OF THE INVENTION
The present invention is based on the object of creating a seal insert that shows sufficient flexibility and still exhibits a relatively good stability. It must be possible to insert this seal insert into a sealing system in which the conversion of an axially acting closing force occurs 90° to a sealing force acting radially on a sealing surface. The object is inventively achieved with a seal insert in which at least one rib-shaped portion respectively proceeds between two corner regions of a rectangular cross-section along the outside wall of the seal insert. A cavity proceeds longitudinally in the center of the seal insert and longitudinal channels are also arranged in each comer region of the seal insert so that the longitudinal channels proceed parallel to the longitudinal cavity. Preferably, the seal insert is a continuous annular ring insert.
Sleeves and similar receptacles made of plastic exhibit a high expansion factor, which is particularly obvious when the temperature changes. Thus, high requirements are set for the seal inserts of such receptacles regarding the flexibility and adjustment given temperature changes. Therefore, they must be very elastic in order to compensate and overcome the expansion fluctuations of the involved components. They must also show a high restoring behavior at low temperatures and must still exert sufficient seal forces in the most disadvantageous conditions. In previous plastic cable fittings, elastic seals made of rubber or silicon have been used, for example, which have a cross-section of an annulus or a circular disc. It is disadvantageous here that these seal inserts with a circular ring profile are respectively situated adjacent only along a generating line of the seal insert at the surface that is to be sealed. A further disadvantage of such seal inserts is that they form an oval when pressed together and tend to collapse. Therefore, pressure is no longer built up against the seal surfaces and the seal becomes defective.
The inventive seal insert comprises a rectangular cross-section, an inner cavity proceeding longitudinally in the insert and additional longitudinal channels extending parallel to the large, centrally proceeding cavity. This seal insert meets the given requirements and, in connection with the rib-shaped portions that proceed longitudinally, is especially appropriate for sealing in seal systems given cable fittings made of plastic.. Besides, the inventive seal insert is especially appropriate for applications wherein the closing force exerted on the seal insert that is inserted into a seal channel acts offset 90° on the adjacent sealing surface, for example as in the given case of cable sleeves. The inventive seal insert is approximately rectangular and preferably square, so that the sealing surface is substantially larger relative to the sealing surface compared to a seal formed of a circular cross-section. The outside press surfaces of the seal insert, however, are provided with rib-shaped portions that proceed longitudinally. These rib-shaped portions multiply the contact pressure surface relative to the sealing surface as compared to a circular profile and prevent transverse inclusions, which may lead to leaks. Preferably, the interior proceeding cavity is also of an oval cross-section, whereby the larger axis of the oval extends in the direction on which the closing force is applied. Thus, the acting closing force is diagonally deflected to the sides and acts more uniformly on the adjacent seating sealing surfaces. Further, smaller longitudinal channels are arranged in the comer regions of the seal insert to extend parallel to the inner cavity. Thus, a sufficient stroke is provided in the corner regions of the seal insert. Moreover, the rigidity of the seal insert is thereby reduced, so that the necessary contact pressure forces can be reduced given the same sealing effect.
In a further development of the inventive seal insert, holes are respectively introduced in the longitudinally extending cavity and/or the longitudinal channels so that the interior stands in connection with the outside environment. This solves the problem of different temperature responses in the outer and inner regions of the seal insert. Tension between the individual sleeve parts, which can have a damaging effect on the sealing conditions, have, in certain instances, resulted due to the chronologically differing temperature characteristics given outside temperature fluctuations up to the inner regions of the seal insert. Thus, for example, given an outside cooling, the outer sleeve shell contracts, whereby the temperature in the interior of the seal insert is still higher so that in a closed state, an extremely high pressure occurs in the interior of the seal insert. This high pressure leads to the permeation of the air to the outside. Given a later heating, the sleeve shell expands again, whereby air in the seal insert is still cold and is also reduced by the previous permeation. This results in a leak during the temperature change that can ultimately lead to a failure of the seal. This process becomes especially obvious when a foam material is used for the seal insert, since the permeation of air then also takes place in the individual pores. Due to the invention of holes in the longitudinally extending cavity or the longitudinal channels, a corresponding air flow occurs to the outside environment so that the cited defects cannot arise. The inventive seal insert is explained in greater detail below with the aid of the Figures.
REFERENCES:
patent: 4179319 (1979-12-01), Lofdahl
patent: 4216351 (1980-08-01), Brandeau
patent: 4654473 (1987-03-01), Roux et al.
patent: 4808772 (1989-02-01), Pichler et al.
patent: 5545851 (1996-08-01), Meltsch et al.
patent: 5979902 (1999-11-01), Chang et al.
patent: 6107574 (2000-08-01), Chang et al.
patent: 0 443 118 (1995-01-01), None
patent: 0 652 619 (1995-05-01), None
Froehlich Franz
Zimmer Rainer
Kincaid Kristine
Nguyen Chau N.
RXS Kabelgarnituren GmbH
Schiff & Hardin & Waite
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