FR2586800A1 - Pyrotechnic initiation device (trigger) - Google Patents

Abstract

Pyrotechnic initiation device (trigger). A wire 8 placed in contact with a pyrotechnic load 10 is supplied with electrical current by a source 12 through a circuit comprising two rods 4, 6; an electric filter 18 is inserted between the source 12 and the rods 4, 6 in order that only a specific signal, supplied by the source 12, causes in the wire 8 the passage of a current which is sufficient to initiate the load 10. Application for protecting a pyrotechnic initiation device (trigger) from untimely connection.

Description

PYROTECHNIC INITIATOR
The present invention relates to a pyrotechnic initiator having increased safety compared to the devices of the prior art.

 It is known to initiate a pyrotechnic charge using a pyrotechnic initiator comprising a wire in which an electric current is passed in order to cause a release of heat capable of initiating a charge serving, for example, as a detonator for a charge. more important.

 Figure 1 attached shows a device of this type. This, bearing the general reference 1, consists of an insulating block 2, which may be ceramic, inside which are two pins 4 and 6. These are joined at one of their ends by a wire 8, called "hot wire", which is in contact with a pyrotechnic charge 10. The other ends of pins 4 and 6 are connected to an electrical power source 12 by the intermediary of two wires 14 and 16. When an electrical signal is sent to the circuit thus formed, the wire 8 is heated by the Joule effect and the load 10 is initiated. However, the operation of such a device is only possible if a certain electrical energy depending on the characteristics of the initiator is supplied.

 Such a system has a significant drawback in that there is a risk of triggering the pyrotechnic reaction by the supply of untimely electrical energy, for example if the device is connected to the mains or any other occasional source of electrical energy.

 The present invention aims to remedy these drawbacks by proposing a pyrotechnic initiator having increased security in the event of untimely connection.

 The pyrotechnic initiator which is the subject of the invention comprises, in known manner, a device for initiating a pyrotechnic charge supplied by an electric power source. According to the invention, this initiator further comprises an electric filter placed between the priming device and the source, this filter being integrated into the priming device and being adjusted so that only a specific signal supplied by the source causes L priming of the load.

 According to another characteristic of the invention, the filter is a "high pass" filter, the transformer of which is a magnetic ferrite circuit with a transformation ratio of approximately 7.

The invention will appear more clearly on reading the description which follows, given by way of purely illustrative and in no way limiting example, with reference to the appended drawings in which:
FIG. 1, already described, is a schematic sectional view of a pyrotechnic initiator according to the prior art, and
- Figure 2 is a view similar to Figure 1 illustrating an initiator according to the invention.

 If we refer to Figure 2, we see that the initiator object of the invention comprises, as in the case of Figure 1, an insulating block 2 in which are the two pins 4 and 6, these der nieras being joined at one of their ends by a wire 8 placed in contact with a pyrotechnic charge 10. There is also the electrical power source 12, but an electrical filter 18 is interposed between the source 12 and the device d initiation of the pyrotechnic charge 10. This filter comprises a transformer 22 associated with a capacitor 24. Thanks to the presence of this filter, only an electrical signal having particular voltage and frequency characteristics can produce in the wire 8 l sufficient energy necessary for the operation of the Initiator.

 By way of test, such a device was produced in which the filter 18 is a "pass-through" filter, the transformer of which is a ferrite magnetic circuit having a transformation ratio of approximately 7. Thus, only a square primary signal of 220 volts peak-peak and frequency 140 Khz causes, in pins 4 and 6 and wire 8, the passage of a current sufficient to initiate the pyrotechnic charge 10, the input mpedance being 300 ohms.

 Safety is further increased by the fact that the filter is incorporated in the load initiating device, the transformer 22 and the capacitor 24 being inside the housing 20 which contains the block 2 and the pins 4 and 6. Thus, the direct connection of the pins to any source of electrical power supply is made impossible.

 As for the applications, they are numerous and varied and such a device can be used whenever it is necessary to protect against accidental manipulation. It can be used, for example, in aeronautics, where currents with a frequency of 400 Hz are used, in domestic distribution, where current is used at 50 Hz, and in fields where DC voltages are used.

Such a device also has effective protection against malicious acts or terrorism because it requires a specific electrical power source known only to the designer to operate it.

Claims (2)

 1. Pyrotechnic initiator comprising a device for initiating a pyrotechnic charge (10) supplied by an electrical power source (12), characterized in that it further comprises an electrical filter (18) placed between the device d priming and the source (12), this filter (18) being integrated into the priming device and being adjusted so that only a specific signal supplied by the source (12) causes the priming of the load (10).  2. Pyrotechnic initiator according to claim 1, characterized in that the filter (18) is a high-pass filter comprising a transformer constituted by a magnetic ferrite circuit whose transformation ratio is approximately 7.