Ammunition and explosives – Igniting devices and systems – Accidental fuse ignition prevention means
Patent
1998-01-02
1999-08-24
Tudor, Harold J.
Ammunition and explosives
Igniting devices and systems
Accidental fuse ignition prevention means
1022025, 1022027, 10220214, F42B 318, F42C 1912
Patent
active
059427175
DESCRIPTION:
BRIEF SUMMARY
This invention relates to an electro-pyrotechnic initiator.
The purpose of this type of device is to be ignited by the passage of an electric current greater than a predetermined threshold value, so as to put a mechanism into action.
The electro-pyrotechnic initiators are intended to be integrated into electro-technical chains. In particular, they are used in safety systems for a car or for other vehicles, for example, in order to activate a safety air-bag. They are also used, for example, in missiles.
Such an electro-pyrotechnic initiator is known, for example, from document U.S. Pat. No. 5,230,287. This known electro-pyrotechnic initiator comprises two electrical pins for supplying current, inserted into a baseplate, a bridge establishing an electrical connection between the two pins, a pyrotechnic composition stored in a receptacle, an electronic circuit comprising a bridge laid down on a wafer, this wafer being connected to the electrical pins for supplying current, and the pyrotechnic composition being compacted in the receptacle and brought together with the micro-component under pressure in the receptacle.
The invention also relates to a method of producing an electro-pyrotechnic initiator, and a safety system for a vehicle comprising one or several initiators.
The initiators used until now have usually consisted of a device comprising two electrical pins, connected by a soldered filament that forms a conducting bridge arranged in contact with a pyrotechnic composition.
The rudimentary aspect of the connection between the pins has the major disadvantage of not providing sufficient control over the ignition.
In more highly developed initiators, the conducting bridge is made on a printed circuit or an equivalent support. Greater precision is then possible.
However major disadvantages remain. In particular, a bead of solder is necessary at the electrical connection between the conducting bridge and the pins for supplying current. This impairs the flatness of the interface of the conducting bridge with the pyrotechnic composition and affects the evenness of the heat exchange. The bead of solder also necessitates to use deposition technology, involving the deposition of drops or of pyrotechnic product paint, technology which is not highly regarded for large scale serial manufacture.
Furthermore, these devices have an architecture which does not equally well provide for receiving a conducting or a semi-conducting bridge.
Another disadvantage of the initiators usually used is that protection against discharges of static electricity is not taken into account. Very serious consequences can result to the user from this.
Regarding the detection of leaks, usually it is done by the injection of helium and then detection through aspiration. This method is time consuming to implement and is not very reliable.
The invention is directed towards remedying these disadvantages.
The aim of the invention is thus an electro-pyrotechnic initiator that permits precise control of an ignition, that is capable of being integrated into a high performance chain calling for a high level of reliability.
Another object of the invention is an initiator capable of equally well receiving a conducting or a semi-conducting bridge, with identical architectures, the semi-conducting bridge providing a more rapid heat exchange with the pyrotechnic composition.
It is also an aim of the invention to provide an initiator that is stable over time.
A further object of the invention is to provide protection against discharges of static electricity.
A supplementary aim of the invention is a technology that makes use of a compacted form of the pyrotechnic composition, that allows the integrity of the interface between the bridge and the composition to be preserved even after long storage.
Another object of the invention is an initiator having a long life due to its gas tight properties.
The invention also has as an object, a very simple method of producing an electro-pyrotechnic initiator having the advantages above.
The invention relates also to a
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Pathe Claude
Trousselle Raphael
Bickford Davey
Tudor Harold J.
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