EP1111326A1 - Electric igniter with a glass casing - Google Patents

Abstract

The electrical detonator has a cylindrical envelope (2), of hard glass, soft glass, or quartz glass, which is open at one end, containing a glow bridge (9), supported by a frame (5) incorporated in the closed end of the envelope. The frame is provided by two electrical leads of a material which is matched to the glass envelope material for ensuring a vacuum-tight seal.

Description

Technical field

The invention is based on a raw form of a glass piston igniter according to the preamble of claim 1. It is in particular a raw form for Application in security technology in automotive applications, especially in Airbag modules or in restraint systems such as belt tensioners. The invention also encompasses the glass piston igniter produced from the raw form.

State of the art

An airbag module for motor vehicle applications is already known from US Pat. No. 5,944,342. but with a conventional detonator.

Presentation of the invention

It is an object of the present invention to provide a raw form of a glass bulb igniter to provide the preamble of claim 1, which improves functional reliability, especially the ignition security and tightness.

This object is achieved by the characterizing features of claim 1. Particularly advantageous configurations can be found in the dependent claims.

Known detonators made of plastic are severely affected by environmental influences. The plastic cover encases a glow bridge made of sheet brass. The open end of the plastic sleeve is sealed with O-rings.

However, the glass bulb igniter according to the invention is vacuum-tight and moisture-tight over a service life of 15 years and in a temperature range between -45 and 80 ° C.

For this purpose, the envelope is a cylindrical glass piston and the supply lines are melted into the glass instead of just mechanically sealed. The Glow plug is a wire pin that can also be coiled similar to the one from the Lamp industry known. A filament can because of its filigree structure well-defined properties are assigned in terms of their resistance, whereby a precisely defined response time of the glass piston igniter is achieved.

The glass piston igniter according to the invention consists of a cylindrical piston with an inner diameter between 4 and 5.5 mm ?? and a frame that in the second end is melted, the frame being sealed in its Part consists of one or more glass-compatible materials. In particular this can be the combination of tempered glass (or soft glass) and with regard to the coefficient of expansion be adapted metallic material. A second variant is Quartz glass and a frame that also prefers a film in the seal made of molybdenum.

characters

Figur 1

ein Glaskolbenzünder-Rohform, im Schnitt, (Figur 1a) und um 90° gedreht (Figur 1b);

Figur 2

das Gestell mit Glühbrücke im Detail;

Figur 3

einen fertigen Glaskolbenzünder.

The invention will be explained in more detail below with the aid of several exemplary embodiments. Show it:

Figure 1

a raw glass bulb igniter, in section, (Figure 1a) and rotated by 90 ° (Figure 1b);

Figure 2

the frame with glow plug in detail;

Figure 3

a finished glass bulb igniter.

Description of the drawings

FIG. 1 shows a raw form 1. It consists of a cylindrical piston tube 2 Tempered glass (e.g. Schott 8252 and 8253 or Corning 1724) with an outer diameter of 6.1 mm and a total length of 55 mm. The wall thickness is about 0.9 mm. The first end 3 of the piston 2 is open for further processing. The second end 4 is closed with a pinch in which a frame 5 is sealed gas-tight. It consists of two external power leads 6 a diameter of 0.7 to 1.5 mm made of iron or nickel (or FeNi alloy) and two butt welded inner electrodes 7 with one 0.4 mm diameter made of molybdenum. These are one at the free end Spade piece 8 flattened, namely over a length of 3 mm and a width of 0.4 mm. About half of the spade piece is bent over one as a wire trained glow plug 9 to hold at their ends. The glow plug 9 is uncoiled and consists of 20 to 35 µm thick constanta wire.

Essential for the reliable functioning of the glass bulb igniter is the im Frame with glow plug formed ohmic resistance. The dimensions of the Individual components (Figure 2) are chosen so that the total resistance is 2 Ω with a tolerance of at most ± 0.2 Ω deviation. It is essential for this i.a. maintaining a precise distance between the two spade pieces, which is 2.0 mm. It is also important that the spade piece has a very good one Contact to the ends of the coil is guaranteed to minimize contact resistance. This can preferably be done by laser welding or resistance welding will be realized. The contribution of the Glow plug and the careful choice of its dimensions. The contribution of the rack, in particular the power supplies and electrodes are only in the range of less than 10 mΩ. Since it is crucial to the response time in glass piston igniters arrives, which must not be longer than 4 ms, a wire of maximum 45 µm thickness selected, 25 to 35 µm, in particular 28 to 32 µm are preferred. As a lower limit a value of 20 µm is recommended, otherwise the stability of the filament suffers. Ultimately, the decisive factor is the mass of the filament.

These dimensions of the glow bridge ensure that the required short time (maximum 4 ms) the temperature (300 ° C) develops the necessary is to detonate the explosives.

This raw form can then be dispatched for filling and then on the first Be closed at the end.

The diameter of the piston is essential since it is large enough must be clean to fill with explosives through the first end of the piston and enable reliably. The filling must be done so that the Explosives reliably reach the second end of the piston and no explosives gets stuck on the inside wall of the piston. Therefore, an inside diameter of the Piston of at least 4 mm required. On the other hand, it should be at most 4.5 mm be. In practice, a value close to the upper limit is sought.

The volume of the piston 2 which is still open at the first end 3 is initially filled with filler material 10, in particular the volume is about 30% Explosives and possibly other fillers such as propellant or solvent, at least so that the glow bridge 9 is covered. The distance of the glow bridge, which is arranged transversely to the axis of the piston, from the wall on the first The end is 0.2 to 0.8 mm. Then the solvent may be removed Drying removed and the finished Glakolbenstünder completed that the first End is melted in air. The filling takes place directly, for example Pump cannula or by preparing the explosive as an emulsion (with solvent) will (but also cannula?).

In the finished application system in the vehicle, the ignition is by means of current passage caused on the filament. Misfire is convenient with the glass bulb igniter locked out.

In a further exemplary embodiment, the piston consists of soft glass, in particular Lead glass (Ph 291) or soda-lime glass (Ph 360) and the electrodes F-wire or Dumet wire (nickel-iron alloy, known per se from the lamp industry, for example Vacovit).

Claims (9)

Glass bulb igniter raw form with a cylindrical bulb (2) with two ends, whose first end is open, and with a glow plug (9) in the piston, which by means of a Frame (5) is held in the piston, characterized in that the piston consists of tempered glass, soft glass or quartz glass, the frame (5) in the second end is melted, the frame consisting of two feed lines, which hold the glow plug (9), the material of the piston and the feed lines are coordinated so that the second end is sealed in a vacuum-tight manner is. Glass bulb igniter raw form according to claim 1, characterized in that the Glow plug (9) is a wire pin or a spiral wire. Glass bulb igniter raw form according to claim 1, characterized in that each Supply line comprises at least one outer power supply and an inner electrode. Glass bulb igniter raw form according to claim 1, characterized in that the one end of the electrode is widened to a piece of spade that is used to hold the The end of the glow plug serves. Glass bulb igniter raw form according to claim 2, characterized in that the The diameter of the helix wire is 20 to 35 µm. Glass bulb igniter raw form according to claim 1, characterized in that the The inside diameter of the piston is 4 to 4.5 mm. Glass bulb igniter raw form according to claim 2, characterized in that the The resistance of the frame with the glow plug is 2 ± 0.2 Ω. Glass bulb igniter raw form according to claim 1, characterized in that the Distance between the electrodes is about 2 mm and the width of the spade pieces is about 0.4 mm. A glass bulb igniter formed from a raw form according to claim 1, wherein the first End sealed and the piston contains at least explosives, the glow plug is completely covered with explosives.

Images