DE102019121477A1 - GAS GENERATOR AND USE OF A FLEXIBLE SUPPORT AS EARLY IGNITION DEVICE IN A GAS GENERATOR - Google Patents

Abstract

The invention relates to a gas generator for a safety device in a motor vehicle, with a housing (12) and a combustion chamber (16) located inside the housing (12), a pyrotechnic fuel (18) and at least one pre-ignition device (16) in the combustion chamber (16). 20) is received, and wherein the pre-ignition device (20) comprises a flexible carrier (22) and at least one pre-ignition means bound to the carrier (22). Furthermore, the invention relates to the use of a flexible carrier (22) as pre-ignition device (20) in one Gas generator (10).

Description

The invention relates to a gas generator for a safety device in a vehicle and the use of a flexible carrier as an early ignition device in a gas generator.

Gas generators supply gas, for example, to fill a gas bag or to drive a seat belt tensioner. For this purpose, the gas generator contains a gas-generating pyrotechnic propellant in a combustion chamber, which can be activated if necessary and which decomposes or burns very quickly with the formation of gaseous products.

The burning behavior of the fuel in the Bonfire case can be controlled and promoted by using an early ignition agent. The term bonfire case is to be understood as a test condition for a gas generator in which an improper or thermal triggering of the gas generator is to be mapped, as can be the case, for example, in the event of a fire in a vehicle in which the gas generator is installed is.

Pre-ignition means are exothermic reacting pyrotechnic compositions, the self-ignition temperature of which is below about 200 ° C. and is thus significantly lower than the self-ignition temperature of the pyrotechnic fuel. The pre-ignition means that the conversion of the fuel is thermally triggered below a critical ambient temperature, so that a timely and controlled reaction to generate gas can take place.

The pre-ignition agent is usually filled in the form of powder, tablets or pellets together with the fuel directly into a combustion chamber of the gas generator. The pre-ignition agent is therefore not fixed, which can lead to an uneven distribution within the combustion chamber and thus to an uneven burn-off when the gas generator is triggered. In addition, the storage stability of the pre-ignition agent is often not optimal.

From the WO 2017/136872 A1 describes a method for producing a pyrotechnic film, in which oxidizing agents and fuels are introduced into a polymer solution. By removing the solvent from the polymer solution, films can then be obtained which have pyrotechnic compositions. The polymer serves as a binder or matrix for the pyrotechnic composition and as an additional fuel. The pyrotechnic foils are to be used in particular as fireworks and for pyrotechnic special effects

The object of the invention is to provide a reliable and flexible pre-ignition device for use in gas generators.

The object is achieved according to the invention by a gas generator for a safety device in a vehicle, with a housing and a combustion chamber located within the housing, a pyrotechnic fuel and at least one pre-ignition device being accommodated in the combustion chamber, and the pre-ignition device having a flexible support and at least one comprises pre-ignition agent bound to the carrier.

The flexible support ensures that the pre-ignition device can be provided in a large number of shapes and geometries and can be arranged within the combustion chamber. This enables better control of the burning behavior, since the flexible carrier can be easily adapted to the type of gas generator used in each case.

In one embodiment, the carrier is formed from a plastic, and the at least one pre-ignition means is embedded in the plastic of the carrier.

An elastomer or a thermoplastic can preferably be used as the plastic, in particular polyvinyl chloride (PVC), polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polystyrene (PS) and / or a combination thereof.

In general, all plastics are suitable as carriers in which the respective early ignition agent has sufficient dispersibility. In addition, the plastic should melt to a sufficient extent at elevated temperatures under bonfire conditions.

Plastics are easy to process and can be produced in various geometries and are particularly well suited to absorbing the pre-ignition agent and at the same time forming a flexible carrier. In addition, the resulting thickness of the carrier can be controlled in a simple manner via the amount of plastic used.

In addition, the plastic can serve as additional fuel when the pre-ignition device is triggered. This ensures that the carrier material is completely burned off. If the oxygen balance is sufficient, the plastic only breaks down into gaseous products, so that no solid components remain that would have to be retained by means of sieving, for example.

The plastic can thus serve both as a matrix and binder for the pre-ignition agent and as a fuel.

The plastic is present in a proportion of 5 to 95 percent by weight, based on the total weight of the pre-ignition device, more preferably in a proportion of 10 to 70 percent by weight or 10 to 50 percent by weight.

The pre-ignition agent is preferably embedded in the plastic of the carrier, that is to say it is distributed within a plastic matrix. The pre-ignition agent can be distributed both uniformly and non-uniformly within the plastic matrix.

The storage stability of the pre-ignition agent is increased by embedding it in the plastic, as a result of which aging effects are reduced and the reliability of the gas generator is increased.

An early ignition device according to the invention has a high intrinsic energy density and a high proportion of bound oxygen. As a result, the burn-up of the pre-ignition device is less dependent on pressure fluctuations, so that proper burn-up is guaranteed even in the event of a strong pressure drop.

The pre-ignition means is a pyrotechnic composition with a low self-ignition temperature of preferably not more than 200 ° C., which is used to activate the fuel in the gas generator according to the invention when the outside temperature is elevated.

The at least one pre-ignition agent can comprise a fuel and optionally an oxidizing agent. Oxidizing agents are added in particular when the fuel alone does not have a balanced oxygen balance.

The fuel can be a material selected from the group consisting of boron, aluminum, silicon, magnesium, iron, titanium, tungsten, copper, carbon, zirconium, alloys of the aforementioned elements, nitrotriazolone, nitrocellulose, guanidinium compounds, in particular guanidinium nitrate, and / or combinations of the aforementioned fuels.

The fuel is present in a proportion of 5 to 95 percent by weight, based on the total weight of the pre-ignition device, more preferably in a proportion of 10 to 90 percent by weight or 20 to 80 percent by weight.

The oxidizing agent can be a material selected from the group consisting of nitrates, oxides and / or mixed oxides of the alkali metals, alkaline earth metals and transition metals, in particular potassium nitrate, barium nitrate, strontium nitrate, sodium nitrate, lithium nitrate, iron oxide and copper oxide, transition metal nitrate hydroxides, chlorates and perchlorates in particular potassium perchlorate, potassium chlorate, sodium perchlorate and ammonium perchlorate, as well as ammonium nitrate, sulfates, phosphates, oxalates, water and / or combinations thereof.

The oxidizing agent, if present, is present in a proportion of 10 to 90 percent by weight based on the total weight of the pre-ignition device.

The choice of the pre-ignition means depends primarily on the desired ignition temperature and the fuel used for the gas generator. The pre-ignition agent must be able to generate sufficiently high temperatures to ignite the fuel.

The burn-off behavior and the properties of the pre-ignition device can also be adjusted using additives, for example plasticizers, stabilizers, release agents, dyes, pigments and / or fillers.

In addition to the pre-ignition device, the pre-ignition device can contain a further pyrotechnic composition which is bound to the carrier. The same components can be used for the further pyrotechnic composition as for the at least one pre-ignition device and the above explanations apply analogously to the pyrotechnic composition.

However, the composition of the further pyrotechnic composition is preferably selected such that it has a higher ignition temperature than the pre-ignition means, in particular an ignition temperature of more than 200 ° C. The further pyrotechnic composition then serves as a secondary charge or booster charge for the early ignition means.

At the same time, the composition of the further pyrotechnic composition is selected so that it can be activated by the early ignition means.

The pyrotechnic composition is particularly preferably a thermite. The term thermite is understood to mean a pyrotechnic composition composed of a metal powder and a metal oxide. The metal powder is preferably selected from the group consisting of Al, Mg, Bi, Ti, Zr, Hf and Si or mixtures thereof. As the metal oxide, an oxide of Si, Fe, Mn, V, Mo, Cu, Zn, Cr, Ti, alone or in Combination with each other. A preferred thermite is a mixture of aluminum powder and iron oxide or aluminum powder and CuO.

Thermites can provide the heat or energy necessary for the activation of the fuel for a period of time sufficient to completely burn off the fuel.

The further pyrotechnic composition, if present, is present in a proportion of 5 to 95 percent by weight, based on the total weight of the pre-ignition device, more preferably in a proportion of 10 to 70 percent by weight or 10 to 50 percent by weight. In the case of using a further pyrotechnic composition, the abovementioned proportions of fuel and oxidizing agent relate to the sum of the proportions in the early ignition device and in the further pyrotechnic composition.

The carrier can have several interconnected layers, with an early ignition agent and / or the further pyrotechnic composition being contained in at least one first layer and a further early ignition agent and / or the further pyrotechnic composition in at least one second layer.

The pre-ignition agent contained at least in a first layer of the carrier and the further pre-ignition agent contained at least in the second layer and / or the further pyrotechnic composition preferably have different ignition temperatures. In this way, the combustion behavior of the pre-ignition device can be further influenced and adjusted to the gas generator. For example, a further pyrotechnic composition can be used to ignite the fuel which itself does not have a sufficiently low decomposition temperature, but can be activated by an early ignition means which is triggered at a sufficiently low decomposition temperature.

The at least two layers of the carrier can also have different plastics. This enables a suitable plastic to be selected depending on the pre-ignition agent used and / or the further pyrotechnic composition. This provides a further possibility of ideally matching the burn-up behavior of the pre-ignition device to the respective gas generator.

The carrier can be designed in the form of a band, so that the at least two layers are arranged flat one above the other.

The carrier can also be designed in the form of a cord or a wick, so that a first layer of the carrier is at least partially enclosed by at least one second layer. In general, a band-shaped carrier in the form of a cord or a wick could also be twisted.

In a preferred embodiment, the carrier has a multilayer structure with an inner layer and a first and a second outer layer, which are arranged on opposite surfaces of the inner layer. The first outer layer and the second outer layer each contain an early ignition agent which has a lower autoignition temperature than an early ignition agent and / or a further pyrotechnic composition in the inner layer.

Such an arrangement makes it possible to use a more difficult to activate early ignition agent or a more difficult to activate further pyrotechnic composition in the inner layer, which can be reliably ignited at an elevated ambient temperature by an early ignition agent with a low autoignition temperature in the outer layers surrounding the inner layer. This is particularly advantageous if a higher energy input is necessary to activate the fuel, which energy input can only be achieved using a more difficult to ignite early ignition agent or a more difficult to ignite further pyrotechnic composition.

Thus, the inner layer thermite can have as a further pyrotechnic composition and the first and the second outer layer nitrotriazolone (3-nitro-1,2,4-triazol-5-one, NTO) as an early ignition agent. Compared to thermite, the nitrotriazolone can be activated at lower temperatures. The heat or energy generated during the decomposition reaction of the nitrotriazolone is used to activate the thermite, which in turn activates the burning of the fuel in the gas generator.

The first and the second outer layer can in turn have several layers, which can also contain different pre-ignition means and / or further pyrotechnic compositions. The carrier can thus have a layer structure which enables a tailor-made burn-off behavior. The ignition temperature of the pre-ignition agent or of the further pyrotechnic composition preferably decreases from the outermost layers of the first and second outer layers to the inner layer.

In such a variant, the first and second outer layers can also have a different number of multiple layers.

The early ignition means or the further pyrotechnic compositions between the The outermost layers and the inner layer function in such an arrangement as transfer charges or as moderators. In this way, not only can the correct triggering of the pre-ignition device be guaranteed, but the time course of the burn-up of the pre-ignition device can also be optimized.

In a preferred embodiment, the first and second outer layers contain the same pre-ignition agent and, if present, the same pyrotechnic composition. Correspondingly, the layer structure of the carrier is symmetrical, in particular mirror-symmetrical, around the inner layer. Such an arrangement ensures a uniform burn on both sides of the carrier and thus a particularly controlled ignition of the pre-ignition means or the further pyrotechnic composition of the inner layer.

The carrier can be in the form of a sleeve, a disc, a tape, a cord and / or a net. The geometry used can be matched to the present gas generator, so that an increased contact surface between the pre-ignition device and the fuel of the gas generator can be achieved.

Likewise, gas generators can be obtained in this way which ideally enable the transfer of heat from external components of the gas generator to the fuel in the event of fire and thus improve the overignition capability from the pre-ignition agent and / or the further pyrotechnic composition to the fuel.

In order to additionally achieve mechanical damping, the carrier can be arranged between an inner wall of the combustion chamber and the fuel. As a result, the fuel can no longer hit the walls of the combustion chamber directly, as a result of which, on the one hand, mechanical loads on the fuel and, on the other hand, rattling noises of the gas generator are reduced.

The carrier can also be arranged within the combustion chamber in such a way that it represents a mechanical damping between the components of the fuel, for example when the fuel is loosely arranged in the form of tablets within the combustion chamber.

The object of the invention is also achieved through the use of a flexible carrier as a pre-ignition device in a gas generator, the flexible carrier comprising at least one pre-ignition means bound to the carrier. The gas generator is preferably a gas generator of the type described above.

• - 1 eine teilgeschnittene Ansicht eines erfindungsgemäßen Gasgenerators mit einer erfindungsgemäßen Frühzündeinrichtung;
• - 2a eine beispielhafte Ausführungsform einer erfindungsgemäßen Frühzündeinrichtung aus 1;
• - 2b eine alternative Ausführungsform einer erfindungsgemäßen Frühzündeinrichtung;
• - 3 ein schematischer Querschnitt eines Trägers der Frühzündeinrichtung mit zwei Schichten; und
• - 4 ein alternativer schematischer Querschnitt eines Trägers der Frühzündeinrichtung mit fünf Schichten.

Further advantages and properties of the invention emerge from the following description and the drawings. In these show:

• - 1 a partially sectioned view of a gas generator according to the invention with an early ignition device according to the invention;
• - 2a an exemplary embodiment of an early ignition device according to the invention 1 ;
• - 2 B an alternative embodiment of an early ignition device according to the invention;
• - 3 a schematic cross section of a carrier of the pre-ignition device with two layers; and
• - 4th an alternative schematic cross section of a carrier of the pre-ignition device with five layers.

In the 1 The illustrated embodiment shows a gas generator 10 such as is used, for example, in a steering wheel of a motor vehicle for a driver airbag. This type of gas generator is also known under the term toroidal gas generator.

The gas generator according to the invention can, however, also have any other design of a gas generator known from the prior art, for example it could be a tubular gas generator.

In addition to other components usually contained in gas generators of this type, which are not described in more detail here, the gas generator 10 a metallic housing 12 on, in which a lighter 14th is used over which the gas generator 10 is activated in the event of an accident via a control (not shown) (normal or intended ignition chain).

The gas generator 10 also has a combustion chamber 16 on using a pyrotechnic composition as fuel 18th contains, the fuel 18th loosely within the combustion chamber 16 present. The fuel 18th is in particular a pyrotechnic propellant.

The fuel 18th can be in the form of a bed of individual propellant bodies which, for example, comprise pressed, in particular dry-pressed, propellant tablets or extruded bodies. The fuel 18th can also be in the form of broken granules, in the form of a monolithic shaped body or in the form of disks or rings lined up in a row.

The fuel 18th may for example contain a guanidine compound, such as Guanidine nitrate. In principle, however, all fuels known to the person skilled in the art from the prior art can be used.

In the combustion chamber 16 there is also an early ignition device 20th . The pre-ignition device 20th is used for self-ignition or thermal ignition of the gas generator 10 if it is exposed to an elevated ambient temperature for a long time, for example under the conditions of a bonfire test or in the event of a vehicle fire.

In such a case, the pre-ignition device ignites initially independently of the normal (intended) ignition chain 20th which is then a controlled activation of the fuel 18th causes the pyrotechnic material in the gas generator 10 Reacts as early as possible or can be thermally activated.

The fuel 18th and the pre-ignition device 20th are coordinated so that the early ignition device 20th one to activate the fuel 18th can provide sufficient heat or energy.

In the in 1 The embodiment shown are two pre-ignition devices 20th inside the combustion chamber 16 intended. These can be identical or consist of different materials and / or have different geometries.

In principle, however, only one or more than two pre-ignition devices can also be used 20th be provided. The number of one or more pre-ignition devices is chosen so that in the event of a bonfire, the fuel is reliably activated 18th he follows.

The pre-ignition device 20th includes a flexible support 22nd and at least one to the wearer 22nd bound pre-ignition.

The pre-ignition device 20th lies in the in 1 embodiment shown as a disc, in particular as a perforated disc, within the combustion chamber 16 before, wherein the longest extension direction of the pre-ignition device 20th parallel to a horizontal direction of extent H of the gas generator 10 runs.

In principle, the longest extension direction of the pre-ignition device could be 20th also along a vertical direction of extent V of the gas generator 10 be arranged. The early ignition device is advantageously located 20th in this case on a wall 23 inside the combustion chamber 16 so that the pre-ignition device 20th a mechanical damping between the fuel 18th and the wall 23 the combustion chamber 16 provides.

In 2a is the pre-ignition device 20th out 1 shown at the carrier 22nd the pre-ignition device 20th is in the form of a perforated disk.

In 2 B is an alternative embodiment of the pre-ignition device 20th shown at the carrier 22nd the pre-ignition device 20th is in the form of a sleeve. The fuel 18th is preferred in such an embodiment within the pre-ignition device 20th arranged. Thus encloses the pre-ignition device 20th the fuel 18th so that it can be activated equally from all sides.

In principle, the carrier 22nd the pre-ignition device 20th in a variety of forms, for example also as a film, tape, cord and / or as a net.

The flexible carrier 22nd is formed from a plastic, in particular from polyvinyl chloride (PVC), polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polystyrene (PS) and / or a combination thereof.

For making the carrier 22nd the plastic is first dissolved in a solvent to form a polymer-binder matrix.

Preferred solvents are selected from the group consisting of tetrahydrofuran (THF), chloroform, toluene, acetone, xylene, alcohols, ethers and / or combinations thereof.

If polyvinyl chloride is used as the plastic, the solvent is particularly preferably tetrahydrofuran.

In principle, solvents are preferred which have a high vapor pressure so that the solvent can be at least partially evaporated in a simple manner.

Alternatively, the plastic can also simply be melted. In this case, the pre-ignition device can also be produced without a solvent.

The pre-ignition agent is then introduced into the polymer-binder matrix obtained, in particular in thin layers by means of a sieve. The pre-ignition agent is thus embedded within the polymer-binder matrix, that is to say it is distributed within the polymer-binder matrix, preferably evenly distributed.

The pre-ignition agent comprises a fuel and optionally an oxidizing agent.

The fuel can comprise a material selected from the group consisting of boron, aluminum, silicon, magnesium, iron, titanium, tungsten, copper, carbon, zirconium, alloys of the aforementioned elements, nitrotriazolone, nitrocellulose, guanidinium compounds, in particular guanidinium nitrate , and combinations thereof.

The oxidizing agent can comprise a material selected from the group consisting of potassium perchlorate, potassium nitrate, potassium chlorate, barium nitrate, strontium nitrate, sodium nitrate, sodium perchlorate, lithium nitrate, iron oxide, copper oxide, ammonium perchlorate, ammonium nitrate, and combinations thereof.

Another pyrotechnic composition can optionally be added. The same components as for the at least one pre-ignition means can be used for the further pyrotechnic composition.

Further additives can also be incorporated into the polymer-binder matrix, for example plasticizers, stabilizers, release agents, dyes, pigments and / or fillers.

The solvent is then at least partially evaporated.

Should a multi-layer structure of the carrier 22nd are achieved, a further layer of a polymer binder matrix is then applied. Pre-ignition means and further components can be introduced into this again in a manner analogous to the first layer, it also being possible for further layers to have only one further pyrotechnic composition and no pre-ignition means.

The compositions of the individual layers can differ from one another.

This process is repeated until the desired number of layers of the carrier 22nd has been received. The carrier is preferred 22nd made up of five or fewer layers.

Eventually residual solvent is evaporated and the finished carrier 22nd receive. This can be brought into the desired shape for the pre-ignition device 20th to form, for example by deforming, cutting and / or pressing.

In the pre-ignition device 20th the plastic is preferably present in a proportion of 5 to 95 percent by weight. The fuel content of the pre-ignition device, without plastic, is preferably from 5 to 95 percent by weight. If an oxidizing agent is contained in the pre-ignition device, the oxidizing agent is preferably present in a proportion of 10 to 90 percent by weight.

If the pre-ignition device contains a further pyrotechnic composition in addition to the at least one pre-ignition device, the further pyrotechnic composition is present in a proportion of 5 to 95 percent by weight, based in each case on the total weight of the pre-ignition device 20th .

In 3 is an embodiment of the pre-ignition device 20th shown in a schematic cross section in which the carrier 22nd of two interconnected layers 24 and 26th is constructed.

The layer 26th has a first pre-ignition agent and the layer 24 a second pre-ignition means and / or a further pyrotechnic composition, the first pre-ignition means of the layer 26th is more easily ignitable than the second early ignition means and / or the further pyrotechnic composition of the layer 24 . In the embodiment shown, the layer 26th Nitrotriazolone as an early ignition agent and the layer 24 Thermit as another pyrotechnic composition.

The layer dissolves accordingly 26th at a lower temperature and, through the decomposition of the nitrotriazolone, provides sufficient heat or energy to remove the thermite from the layer 24 to activate.

In 4th is a further embodiment of the pre-ignition device 20th shown in a schematic cross-section, in which the carrier 22nd an inner layer 28 , one on top of the inner layer 28 arranged first outer layer 30th and an underside of the inner layer on an opposite side from the upper side 28 arranged second outer layer 32 having.

The first outer layer 30th also has several layers itself 30a and 30b on, and the second outer layer 32 multiple layers 32a and 32b , with the layers 30b and 32b closer to the inner layer 28 lie than the layers 30a and 32a .

The layers are preferred 30a and 32a as well as the layers 30b and 32b made of the same materials, so that a layered structure of the carrier 22nd results that are symmetrical, in particular mirror-symmetrical, around the inner layer 28 is around.

The outermost layers preferably have 30a and 32a an early ignition agent with the lowest ignition temperature, corresponding to the outermost layers 30a and 32a the most temperature-sensitive layers of the support 22nd .

The inner layer 28 in contrast, a pre-ignition agent and / or a further pyrotechnic composition with the highest ignition temperature preferably has the inner layer 28 is accordingly the most temperature-insensitive layer of the carrier 22nd .

The one between the outermost layers 30a and 32a and the inner layer 28 arranged layers 30b and 32b accordingly contain an advance ignition agent and / or another pyrotechnic composition with an average ignition temperature and serve as transfer charges between the outermost layers 30a and 32a and the inner layer 28 .

The pre-ignition agent is preferably in the layers 30a and 32a Nitrotriazolone and the further pyrotechnic composition in the inner layer 28 Thermite. In the layers 30b and 32b a transfer charge is preferably used, which is based on the implementation of the pre-ignition of the layers 30a and 32a the further pyrotechnic composition in the inner layer 28 can light reliably.

In this way, the burn-up behavior of the pre-ignition device 20th Controlled in a particularly good way and the fuel 18th of the gas generator 10 can be reliably activated.

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• WO 2017/136872 A1 [0006]

Claims (12)

Gas generator for a safety device in a motor vehicle, with a housing (12) and a combustion chamber (16) located within the housing (12), wherein a pyrotechnic propellant (18) and at least one pre-ignition device (20) are received in the combustion chamber (16), and wherein the pre-ignition device (20) comprises a flexible carrier (22) and at least one pre-ignition means bound to the carrier (22). Gas generator after Claim 1 , characterized in that the carrier (22) is formed from a plastic, in particular from polyvinyl chloride (PVC), polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polystyrene (PS) and / or a combination thereof, and that the at least one pre-ignition means is embedded in the plastic of the carrier (22). Gas generator after Claim 1 or 2 , characterized in that the at least one pre-ignition means comprises a fuel selected from the group consisting of boron, aluminum, silicon, magnesium, iron, titanium, tungsten, copper, carbon, zirconium, alloys of the aforementioned elements, nitrotriazolone, Nitrocellulose, guanidinium compounds and / or combinations thereof. Gas generator according to one of the preceding claims, characterized in that the pre-ignition agent comprises an oxidizing agent selected from the group consisting of nitrates, oxides and / or mixed oxides of alkali metals, alkaline earth metals and transition metals, transition metal nitrate hydroxides, chlorates and perchlorates, ammonium nitrate, sulfates, Phosphates, oxalates, water and / or combinations thereof. Gas generator according to one of the preceding claims, characterized in that the carrier (22) has a further pyrotechnic composition bound to the carrier (22). Gas generator according to one of the preceding claims, characterized in that the carrier (22) has several interconnected layers (24, 26, 28, 30, 32), at least one layer (24, 26, 28, 30, 32) having a Early ignition means and in at least one further layer (24, 26, 28, 30, 32) an early ignition means and / or a further pyrotechnic composition is contained. Gas generator after Claim 4 , characterized in that the carrier (22) has an inner layer (28) and a first outer layer (30) and a second outer layer (32) which are arranged on opposite surfaces of the inner layer (28), the first outer layer (30) and the second outer layer (32) each contain a pre-ignition agent which is more easily ignitable than a pre-ignition agent or another pyrotechnic composition in the inner layer (28). Gas generator after Claim 5 , characterized in that the first and second outer layers (30, 32) contain the same pre-ignition agent. Gas generator according to one of the preceding claims, characterized in that the carrier (22) is in the form of a sleeve, a disk, a band, a cord and / or a net. Gas generator according to one of the preceding claims, characterized in that the carrier (22) is arranged between a wall (23) of the combustion chamber (16) and the fuel (18). Use of a flexible carrier (22) as a pre-ignition device (20) in a gas generator (10), the flexible carrier (22) comprising at least one pre-ignition means bound to the carrier (22). Use after Claim 11 , characterized in that the gas generator (10) is a gas generator according to one of the Claims 1 to 10 is.

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