DE1115629B - Electric spark igniter, especially for propellant and projectile charges - Google Patents

Description

The invention relates to an electric spark igniter, especially for propellant and projectile charges, with a spark gap between two electrodes, one of which is designed as a detonator sleeve can be.

Electrical spark ignitors are known in which there is a dielectric between the two electrodes is present in the form of a thin insulating layer which is partially formed thin to to let the spark pass more easily here. The dielectric only has the task of insulation with the spark igniter, however, there is still a risk of an explosion after assembly present, which can be triggered by stray currents.

The object of the invention is, in the case of the spark igniter mentioned at the beginning, after assembly to exclude the risk of explosion and make the spark igniter independent of stray currents or to make it insensitive. This is achieved according to the invention in that the spark igniter mentioned at the beginning of the spark gap by a arranged between the electrodes and with these related semiconductor layer is formed such characteristics and thickness that the ignition current creates a spark in this layer. By using the semiconductor layer is on the one hand a control of the ignition head by the degree of its resistance after assembly without Risk of explosion as well as its independence from stray currents, since the Selected control voltages and intensities corresponding to the stray currents in one Area where they remain very weak, on the other hand a safe explosion of the ignition head is guaranteed, as soon as the voltage at the ends of the semiconductor reaches a value that the knee of the not corresponds to a linear characteristic, i.e. corresponds to an intensity that exceeds the critical intensity, so that an ignition current is generated in the semiconductor layer, which the ignition by means of the Causes spark.

The invention is explained below with reference to the drawing, for example.

1 and 2 show in an axial section two embodiments of an electrical device according to the invention Ignition head for cartridge cases.

In the embodiment shown, it is assumed that the combat arrangement to be ignited carries a voltage source, e.g. B. a capacitor, which can be loaded at the right time.

Electric spark igniter,
especially for propellant and projectile charges

Applicant:

Brevets Aero-Mecaniques SA,
Geneva (Switzerland)

Representative: Dr. H. Wilcken, patent attorney,
Lübeck, Breite Str. 52-54

Claimed priority:
Luxembourg of October 29, 1957

In a manner known per se, the device contains two metal electrodes 2 and 3 which can be connected to the two poles of the capacitor 1. Between these electrodes is a part 4 made of a semiconductor material with such characteristics and in particular with such a thickness that the discharge 1 of the capacitor through this part connecting the electrodes causes the transition of a spark in this part, which ignites the primary charge 5 of the igniter Consequence. A metalloid or a metalloidic anhydride is expediently used as the semiconductor material, which has a relatively low melting point and preferably a boiling point which allows it to be atomized in a vacuum. In particular, selenium (Se), germanium (Ge), vanadium pentoxide (V ₂ O ₅ ) and silicon monoxide (SiO) can be used.

The following bodies, among others, can also be used:

Silicon (Si) ₅

Silicon sesquioxide (SiO-SiO ₂ ),

Cerium dioxide (CeO ₂ ),

Cadmium sulfide (CdS),

Cadmium Selenure (CdSe),

Antimony sesquisulfide (Sb ₂ S ₃ ),

Aluminum antimony (Al-Sb),

Gallium antimony (Ga-Sb),

Uranium dioxide (UO ₂ ),

Cadrnium oxysulphide (CdS-CdO),

Cadmium Oxyselene (Cd Se-CdO).

109 709/131

The semiconductor material is expediently applied in the form of a membrane or a thin layer 4, of which at least a small zone (which can be on the order of a fraction of a square millimeter) is in contact with one side with one electrode and the other side with the other electrode . The thickness of the semiconductor layer separating the electrodes in this way is determined in each case by experiments so that the desired result is achieved. In a special case, in which the voltage supplied by the voltage source was in the order of magnitude 10OV (capacitance in the order of magnitude of 2 μΡ), a thickness the size of the micron gave satisfactory results.

The breath 4 of semiconductor material is expediently made by the known method of evaporation Applied in a high vacuum, with which as a result of the measurement of the amount of substance to be evaporated and the Control of the exposure time of the steam jets during the sputtering of the semiconductor material a layer more precisely uniform thickness can be produced.

According to an advantageous embodiment, one of the electrodes (the electrode 2 in the figures) is formed by an axial conductive rod, the upper end of which is closed off by an area with a very small surface (eg less than 0.2 mm ² ). This electrode 2 is held by an insulating filling 6 (e.g. made of ceramic or a synthetic resin), which is chosen so that the membrane 4 can be applied under favorable conditions to its flat upper side, which is connected to the upper end surface of the electrode 2 cuts off. This insulating filling is located in a cylindrical sleeve 3 made of an electrically conductive material, which forms the second electrode and is arranged coaxially with the electrode 2. In the special case considered above, the inner diameter of the sleeve was 38 mm.

The device has yet to be completed by means of the current from the Guide the sleeve 3 up to the section (the top of the membrane 4), which is immediately adjacent to the section (the underside of the same membrane) is opposite to that with the upper end face of the electrode 2 is in contact. These devices must be designed in such a way that the heat of the in the skin 4 between these two surface sections produced spark without hindrance is transferred to the primary charge 5, which is believed to be above the Skin 4 is located.

One of the embodiments described below can be used for this purpose, among other things.

According to the first of these embodiments (FIG. 1), the entire upper side of the membrane 4 covered with a thin conductive layer 7, which with at least part of its edges in electrical contact with the inner surface of the sleeve 3 is. This layer 7 is also expediently in the Evaporated to a high vacuum, as described above for the membrane 4.

To form the layer 7, a suitable metal that can be evaporated at the same time is expediently used, which preferably evaporates at a temperature which is higher than that previously applied to the insulating material 6 Semiconductor material lies. The indium is a particularly interesting metal for the production of the Layer 7 due to its rather low melting point (156 ° C), its high boiling point (above 1400 ° C) and its slight evaporation in a vacuum. This metal has against atmospheric Influences stability properties which are comparable to those of silver, its melting temperature is six times as big. In addition, indium is a malleable metal. It is deposited on evaporation in granular form, but adheres very firmly to the membrane 4.

In any case, a conductive ring 8 pressed into the sleeve 3 can be arranged above the layer 7 which is pressed against the layer 7 and a good electrical contact between the sleeve and the layer guaranteed. Its interior can expediently serve to accommodate the primary charge 5, which is brought to the desired degree of compression.

In this training, a small central portion of the membrane 4 is apparently between the pressed into both electrodes, so that the spark arises in this section, which is caused by evaporation pierced the layer 7, if the thickness of the same is chosen correctly, causing the inflammation of the Charge 5 permitted.

In practice, the thickness of the layer 7 can be very small. It is chosen so large that it can be without Destruction can be traversed by the current, which the ignition spark in the layer of semiconductor material should produce. An indium layer between V2 and 1 micron thick gives good results delivered.

According to a second embodiment (FIG. 2), on the inside of the sleeve 3, a radially lying conductive one Finger 9 attached, the end of which with the cuticle 4 at the point of the upper end face of the electrode 2 comes into contact. The charge 5 is then immediately above the pellicle 4 and the finger 9 condensed.

The resulting m the membrane 4 between the end of the finger 9 and the axial electrode 2 The spark can then evidently ignite the charge 5 immediately.

The above ignition heads are particularly easy to manufacture and produce very uniform, constant ones Results, in particular due to the precise setting of the sensitivity threshold thanks to the special Properties of the semiconductor body.

In addition, these ignition heads have an easily measurable electrical resistance, what for theirs Interesting test is which one can undertake by taking it from a stream allows a voltage to flow through which is smaller than the limit voltage above which a spark passes would.

As an example, it should be stated that this limit voltage is only 30 V with an indium layer 1 micron thick and an SiO — SiO ₂ —ScMcM 0.5 micron thick.

The initial electrical resistance of the detonator prior to the filling of the explosive mixture of the In reality, the primary charge is generally high. After filling and compaction of the explosive Mixture on the membrane 4, however, the electrical resistance decreases considerably and becomes easily measurable.

Finally, these ignition heads are very little sensitive to stray currents, which from

static electricity or friction and which, without producing a spark, can discharge through the semiconductor body. The manufacture of these ignition heads is easy, theirs mechanical strength is sufficient, and the tolerances are easy to maintain in their manufacture.

Claims (7)

PATENT CLAIMS: 1. Electric spark igniter, especially for propellant and closed charges, with a spark gap between two electrodes, one of which can be designed as an igniter sleeve, characterized in that the spark gap is formed by a semiconductor layer (4) arranged between the electrodes and connected to them. such parameter and thickness is formed that the ignition current generates a spark in this layer. 2. Electrical spark igniter according to claim 1, characterized in that the semiconductor layer (4) is created in a manner known per se by vapor deposition in a high vacuum. 3. Electrical spark igniter according to claim 1 or 2, characterized in that the half leather layer (4) covered against the primer (5) by an electrically conductive layer (7) which is in contact with the outer electrode (3). 4. Electrical spark igniter according to claim 3, characterized in that the conductive layer (7) is about 1 micron thick. 5. Electrical spark igniter according to claim 3 or 4, characterized in that the conductive The metal forming layer (7) has a higher evaporation point than the semiconductor substance (4). 6. Electrical spark igniter according to claim 3 to 5, characterized in that the conductive Layer (7) consists of indium. 7. Electrical spark igniter according to one of claims 1 to 6, characterized in that the primer (5) is housed in a conductive ring (8) which is in conductive connection with the outer electrode (3) and the conductive layer (7). Considered publications:
German Patent No. 1036138;
German interpretative document No. 1039 434. 1 sheet of drawings © 109 709/131 10.61