Electricity: electrothermally or thermally actuated switches – Thermally actuated switches – With fusible – combustible or explosive material
Reexamination Certificate
2000-03-30
2002-12-17
Feild, Lynn D. (Department: 2835)
Electricity: electrothermally or thermally actuated switches
Thermally actuated switches
With fusible, combustible or explosive material
C337S182000, C337S185000, C337S405000, C361S115000
Reexamination Certificate
active
06496098
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a pyrotechnic active element for severing media and/or fluids.
DE 42 11 079 A1 and DE 44 22 177 describe pyrotechnically acting fuse elements which have a housing having a hollow space formed therein through which extends transversely with respect to the longitudinal extent thereof, an electrical conductor to be severed in the event of an overcurrent. Arranged in the hollow space is a severing piston which, upon ignition of a pyrotechnic charge, can be moved forwards in the direction of the conductor in order to sever the latter.
The assembly and the construction of the known pyrotechnic fuse elements are extremely costly and the pyrotechnic elements, such as the electrical ignition element and charge and also the severing piston, are to be produced specifically according to the respective needs of the client, which is cost-intensive.
SUMMARY OF THE INVENTION
The underlying object of the invention is to develop a pyrotechnic active element having a reduced number of components to be built up separately during the assembly.
In order to achieve this object, there is proposed in accordance with the invention a pyrotechnic active element which is provided with
a base element,
an electrical ignition element which is arranged on or in the base element,
a pyrotechnic charge which can be ignited by the ignition element, and
a severing element which has a severing tool and a holding element holding the latter,
wherein the holding element is connected in a sealed manner to the base element and this connection is releasable upon ignition of the pyrotechnic charge.
The active element in accordance with the invention has electrical ignition element, as it were, as a support for the pyrotechnic charge, and, for holding the terminal contacts of the ignition element, it has a base element to which the cutting element is connected. This connection is moisture-tight and, in particular, is gas-tight, so that the pyrotechnic charge is not rendered inoperative by external influences (penetration of moisture) during the storage of the pyrotechnic active element. On the one hand, the mechanical connection of base element and severing element is mechanically secure such that the two portions do not unintentionally separate from each other during handling and in particular during mounting in a primary unit (for example installation in the housing of an electrical fuse element). On the other hand, the connection of base element and severing element must reliably become detached when the pyrotechnic charge is ignited in accordance with the requirements, without a considerable force being required for this purpose, so that all of the energy released upon ignition of the pyrotechnic charge is converted into kinetic energy of the severing element.
As a result of the active element in accordance with the invention being a self-contained component, an active element once ignited can be removed from its primary unit and replaced with a new active element.
The pyrotechnic active element in accordance with the invention is generally to be used in primary units in which one is concerned with severing or interrupting a medium (for example an electrical conductor) or a flowing fluid (flow of liquid or gas, or viscous substances). The severing tool of the severing element is made of a suitable material (for example metal, ceramics, plastics) depending on the properties and fields of use of the medium or fluid. In the case of the use of the active element in accordance with the invention in an electrical fuse element, the severing tool consists of a non-conductive material, preferably plastics, in which case materials of the raw-material groups polyamide, polycarbonate, polyphenylene sulphide or suchlike with mineral, organic or inorganic fillers are to be mentioned here, in particular.
In an advantageous development of the invention, it is provided that the detachable connection between the base element and the severing element is material-locking, friction-locking and/or form-locking up to a minimum strength, something which can take place in particular by gluing, (ultrasonic) welding, caulking, camming or locking together.
The connection between the severing element and the base element is preferably provided with predetermined breaking points which break open when the pyrotechnic charge explodes and release the severing element. The severing element of the active element in accordance with the invention has the severing tool and a holding element which holds the latter and is preferably constructed in one piece with the severing tool.
In an advantageous development of the invention, in order to achieve the tightness in the unit of the severing element and the base element, at least one O-ring is provided. This sealing ring is preferably arranged in a circumferential groove of the base element or the severing element and rests tightly against the respective other element in the region in which it protrudes above the circumferential groove. The holding element of the severing element (or alternatively the base element) preferably has a protruding encompassing collar, which surrounds the base element (or alternatively the holding element).
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Kern Heinz
Mosig Wolfgang
Dynamit Nobel GmbH Explosivstoff-und Systemtechnik
Feild Lynn D.
Vortman Anatoly
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