Miniature electro-pyrotechnic igniter, and ignition head for the same

Abstract

An electric non-pyrotechnic ignition head (100) suitable for use in an electro-pyrotechnic igniter (1), comprising: a housing (102) defining a front opening (106); —an electrically insulative, thermally conductive bridge filament support body (130) that is at least partly disposed in said front opening, and that defines a frontal heating surface (132b); and a bridge filament (120) including at least one cross-over portion (122) that extends over the frontal heating surface (132b) of the bridge filament support body (130).

Description

FIELD OF THE INVENTION[0001]The present invention relates to a miniature electro-pyrotechnic igniter suitable for use in miniature spacecraft, and to an ignition head for the same.BACKGROUND[0002]Spacecraft, and in particular miniature spacecraft such as cubesats, place stringent demands on, inter alia, the volume, weight, safety and reliability of their components. Common components include cool gas generators and rocket motors, both of which may include electro-pyrotechnic ignition heads.[0003]A conventional electro-pyrotechnic ignition head may typically include an electrically resistive bridge wire that is at least partially embedded within a pyrotechnic primer charge. By passing an electric current through the bridge wire, the bridge wire may be heated to set off the primer charge. The primer charge may in turn ignite a further pyrotechnic charge, such as a cool gas generator charge in the case of a cool gas generator, or a propellant grain in the case of a rocket motor.SUMMARY...

AI Technical Summary

Benefits of technology

The present invention relates to a miniature, lightweight, safe, and reliable ignition head for use in an electro-pyrotechnic igniter. The ignition head features a bridge filament with cross-over portions that extend over a frontal heating surface of an electrically insulative, thermally conductive bridge filament support body, allowing for uniform heating of an end face of a pyrotechnic charge that is in contact with the heating surface. The ignition head also includes a shield film that acts as an ignition retardation control, preventing accidental ignitions and ensuring a minimum amount of electric ignition energy is required for ignition. This makes the ignition head conveniently tunable for different ignition times. The invention also provides an electro-pyrotechnic igniter suitable for use in spacecraft, such as cubesats.

Problems solved by technology

One drawback of such conventional ignition heads, in particular when used in cool gas generators, is that they may not be able to uniformly heat and ignite an end surface of an elongate, for instance cylindrical, cool gas generator charge.

Instead, they may unevenly heat the end surface and cause only a certain spot thereof to ignite, as a result of which the charge may undergo a decomposition reaction in a non-uniform, irregular fashion.

Another drawback of such conventional ignition heads is that the amount of electric energy required to set off the primer charge may be in the order of a tenth or several tenths of a Joule.

Although this low ignition threshold renders the ignition head fast and responsive, it also entails the inherent risk that the primer charge is unintentionally fired when the relatively low amount of electric energy is generated via, for instance, magnetically-induced currents or electromagnetic radiation.

S&A mechanisms, however, are typically mechanical in nature, and relatively large and heavy.

They may, for instance, easily have a mass of 500 grams, which makes them unsuitable for use in miniature satellites whose overall allowed maximum mass may be as low as 1.33 kg.

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