CN110891924A

CN110891924A - Gas generating device for inflating an airbag comprising a second powder charge to reduce the risk of explosion

Info

Publication number: CN110891924A
Application number: CN201880029205.9A
Authority: CN
Inventors: 保罗·菲利普·科德
Original assignee: Seva Technologies SAS
Current assignee: Seva Technologies SAS
Priority date: 2017-04-03
Filing date: 2018-04-03
Publication date: 2020-03-17
Also published as: WO2018185426A1; FR3064569A1; EP3606894A1; FR3064569B1

Abstract

The invention relates to a gas generator for inflating an airbag, consisting of a first chamber containing a first pyrotechnic composition and a second chamber containing a second composition, said first and second chambers being in communication with each other, the first composition being a solid propellant capable of controlling the second composition consisting of a mixture of at least one oxidizing charge and 10 at least one reducing charge, the first chamber being formed in a first casing resistant to a given operating pressure of the first pyrotechnic composition, the second chamber being formed in a second casing resistant to a given lower operating pressure of the second composition, the first and second casings being located in a housing, the second casing having at one 15 end a metal door defining a volume in communication with the outside through at least one gas escape opening formed in the housing, is characterized in that: the second composition is a powder mixture of at least two components, the first component being ammonium perchlorate, ammonium nitrate, potassium nitrate or basic copper nitrate and the second component being a carbon-20 hydrogen-oxygen-nitrogen reducing derivative derived from an amino or nitrate derivative of guanidine, oxamide, urea, triazole, tetrazole, the powder mixture being formed from particles having a particle size greater than or equal to 20 μm and a bulk density of from 0.7 to 1.1.

Description

Gas generating device for inflating an airbag comprising a second powder charge to reduce the risk of explosion

Technical Field

The present invention relates to a gas generating apparatus for inflating a safety system of the airbag type to protect an occupant of a motor vehicle.

The invention relates more particularly to a gas-generating device for inflating an airbag, said gas-generating device being constituted by a first chamber containing a first pyrotechnic composition, referred to as first charge, and a second chamber containing a second composition, referred to as second charge, the first and second chambers being in direct or indirect communication with each other, the first composition being a solid propellant capable of controlling the second composition constituted by a mixture of at least one oxidizing charge and at least one reducing charge, the first chamber being formed in a first pressure-resistant casing of said first pyrotechnic composition, the second chamber is formed in a second pressure-resistant casing of said second composition, the first and second casings being located in the outer casing, the second casing having a metal door at one end, the metal door defines a volume communicating with the outside through at least one gas escape opening formed in said housing.

Background

From the application WO2008053097 a gas generating device is known, comprising one chamber, called first chamber, for the storage and combustion of a pyrotechnic compound, called first compound, said first chamber having at least one orifice, called exhaust orifice, and another chamber, called second chamber, for the storage and decomposition of a compound, called second compound, said first and second compounds forming an explosive charge of the gas generator and being adapted so that the second compound can be decomposed by the combustion products of the first compound, said second chamber having in operation at least one opening, called inlet, through which the combustion products of the first compound can enter.

Also known from application WO2007/068856 is a gas-generating device for a safety system comprising an explosive charge formed at least by a first pyrotechnic compound in a first chamber, the explosive charge being initiated by at least one of a second chamber having an enhancer charge and an initiator for the second compound, the decomposition of which is controlled by the combustion products of the first compound, the combustion products of the first compound and the combustion products of the second compound taking place in a low containment volume through interaction of a redox reaction, the first chamber communicating with a second chamber provided at a first region adjacent to said first chamber through peripheral gas escape openings, and closing said second compound at the second region on the one hand, and closing means forming obstacles for the passage of gas on the other hand, said obstacle-forming means being mounted between said first region and said second region and being arranged to allow the passage of gas through a central portion and to prevent it from passing through a periphery of sufficient permeability The edge portion, so that the interaction volume remains somewhat restricted.

Further examples of gas generating devices are also described in applications WO2008/050006 and WO 2004/091981.

Generally, the gas generator of the above application provides: it is preferred to use as the first compound a composite material or a Lova type propellant and preferably to use as the second compound an additive based on a guanidine derivative in the form of a powder or granules or pellets and ammonium nitrate.

However, the second compound used in the form of powder has a disadvantage in that its physical form changes with time, thereby failing to ensure uniform properties. They also require a large second chamber making prior art gas generators using powdered second compounds relatively bulky.

The second compounds used in pellet form have the disadvantage of being sensitive to the different effects to which they are subjected. In particular, the pellets of the second compound tend to disintegrate under mechanical, thermal or physicochemical action (e.g. moisture), rendering the second compound potentially explosive. Furthermore, the compound in pellet form provides less than satisfactory reaction kinematics than the powdered compound.

The present invention aims to solve this problem by providing a gas generation system that does not have the drawbacks of the gas generation systems of the prior art, in particular by limiting or even eliminating the risk of explosion while ensuring reproducible and constant performance over time.

The present invention is also directed to providing a gas generating system that prevents the formation of harmful dust during the generation of combustion gases.

The present invention is also directed to a recyclable gas generation system.

Disclosure of Invention

To this end, and according to a first aspect, the invention provides a gas-generating device for inflating a safety system of the airbag type, said gas-generating device being constituted by a first chamber containing a first pyrotechnic composition, referred to as first charge, and a second chamber containing a second composition, referred to as second charge, the first chamber and the second chamber being in direct or indirect communication with each other, the first composition being a solid propellant capable of controlling the second composition constituted by a mixture of at least one oxidizing charge and at least one reducing charge, the first chamber being formed in a first casing that is resistant to the operating pressure of said first pyrotechnic composition when [ at ] a given operating pressure of said first pyrotechnic composition, the second chamber being formed in a second casing that is resistant to a given lower operating pressure of said second composition, the first casing and the second casing being connected [ and ] located in a housing, the second housing has a metal door at one end defining a volume communicating with the outside through at least one gas escape opening formed in the outer shell, the gas generating device being superior in that: the second composition is a powder mixture of at least two components, the first component being ammonium perchlorate, ammonium nitrate, potassium nitrate or basic copper nitrate, the second component being a reducing carbon-hydrogen-oxygen-nitrogen derivative derived from an amino derivative or nitrated derivative of guanidine, oxamide, urea, triazole, tetrazole, the powder mixture being formed from particles having a particle size greater than or equal to 20 μm and a bulk density of from 0.7 to 1.1.

The second compound consisting of particles having a particle size of at least 20 μm and a bulk density of 0.7 to 1.1 has the effect of providing a reaction that is stable over time and requires less reaction space than the powdered second compounds of the prior art. Therefore, satisfactory reaction kinematics can be obtained in an optimum space. The risk of explosion is also eliminated and the performance of the gas generating device is rendered reproducible and constant over time.

Apparent density means the mass of the mixture in grams/volume of the mixture in cm without compression³Meter) of the ratio. The density is in Kg/m³Or 1000 × d.

In addition, in the present invention, when at least 90% of the particles constituting the mixture have a particle size and an apparent density within the above ranges, it is considered that the powder mixture is formed of particles having a particle size of 20 μm or more and an apparent density of 0.7 to 1.1.

Advantageously, the powder mixture is formed from particles having a particle size of 20 μm to 100 μm, preferably 20 μm to 60 μm, preferably 30 μm.

Advantageously, the mixture is a eutectic.

Advantageously, the powder mixture is co-milled. The powder mixture is then characterized by a homogeneous appearance. An advantage of the co-milled powdery mixture formed from particles having a particle size of at least 20 μm and an apparent density of 0.7 to 1.1 is that the stability of the mixture in time and space is improved, ensuring satisfactory stable and reproducible reaction performance over time. The final co-milling operation improves the intermixing between the components, reduces the dispersion of the particle size of the mixture, and maintains a bulk density of 0.7 to 1.1.

Another embodiment consists in spraying an aqueous solution of the components in the form of pellets (print). These pellets may be used with or without crushing. Advantageously, they have an apparent density of 0.7 to 1.1.

Advantageously, the second composition is adjusted so that the oxygen balance of the gas produced by the reaction of the first and second compositions at the outlet of the generating device is greater than-5%, advantageously between-5% and + 1%, preferably between-3% and + 1%.

Advantageously, the first housing of the first chamber withstands an operating pressure of more than 5 MPa.

Advantageously, the first housing of the second chamber withstands an operating pressure of less than 15 MPa.

Advantageously, the second housing of the second chamber withstands an operating pressure of more than 3 MPa.

Advantageously, the second housing of the second chamber withstands an operating pressure of less than 30 MPa.

Advantageously, the operating pressure of the second chamber (advantageously the main gas generator of the generator) is less than 15MPa (150 bar), preferably less than 10MPa (100 bar), and advantageously less than 5MPa (50 bar).

Advantageously, the volume of gas generated by the second chamber covers a range of 0.25 moles to more than 4 moles.

According to a first embodiment, the second composition consists of guanidine nitrate and ammonium nitrate.

According to another embodiment, the second composition consists of guanidine nitrate and basic copper nitrate.

Advantageously, the first housing has at least one initiator which can be activated by external control with reinforcing and intermediate fillers.

Advantageously, the first charge is a propellant having an operating pressure of less than 30MPa and a burning time in the range of 0.015 seconds to 2.5 seconds.

Advantageously, the door has one or more apertures defining a surface of greater permeability than the gas escape opening.

Advantageously, the first chamber communicates with the second chamber via a nozzle defined to ensure sonic flow of gas from the first chamber to the second chamber.

Advantageously, the nozzle and the door are arranged at a distance of less than 40mm from each other.

Advantageously, the first housing has, on its outer front end side, an initiator which can be activated by external control provided with a reinforcing charge, and has, on its inner front end side, a central nozzle; a second housing closed at an outer front end side thereof has a door at an inner front end side thereof; said shell connects the two shells in an orientation in which their respective inner front ends face each other and are separated by an intermediate volume, characterized in that this volume communicates with the outside through at least one opening.

According to an alternative embodiment, the first chamber is in direct communication with the second chamber, the door being located at the opposite end of the first chamber, and the volume in communication with the outside being located downstream of the second chamber.

Such a generator device is advantageous in that it provides reproducible and stable performance, the second charge remaining stable in terms of construction: it remains in powder form and its density does not change. Furthermore, there is no segregation of the components.

As will be discussed below, the first charge is a propellant composed of a binder and a filler, which, unlike the pellets, cannot form an explosive mixture if the components are separated.

Drawings

Other objects and advantages of the invention will appear from the following description, with reference to the accompanying drawings, in which:

figure 1 shows a gas-generating apparatus according to a first embodiment of the invention.

Figure 2 shows a schematic view of the shape of a first charge mass used with the gas-generating device.

Figure 3 shows a gas-generating apparatus according to another embodiment of the invention.

Fig. 4 shows a gas-generating device according to another exemplary embodiment of the invention.

For purposes of clarity, the same or similar elements of different embodiments are designated by the same reference numeral throughout the drawings.

Detailed Description

A gas generating apparatus according to a first exemplary embodiment of the present invention is described with reference to fig. 1.

The gas generating device shown is a generator device for inflating a 110 liter passenger airbag. It is made up of a first chamber 1 containing a first pyrotechnic composition, called a first charge, and a second chamber 2 containing a second composition, called a second charge, which can be packaged in a cartridge. The second filler can be controlled by the first composition.

The first chamber 1 is formed in a first housing 1A resistant to the operating pressure of said first pyrotechnic composition. Similarly, a second chamber 2 is formed in a second housing 2A resistant to the operating pressure of the second composition. The first casing 1A and the second casing 2A are connected to each other by a housing 10A.

The first housing 1A has an initiator 15 on its outer front end 11 side and a central nozzle on its inner front end 12 side, said initiator 15 being activatable by external control with a reinforcing charge. The nozzle is used to control combustion of a first charge in the gas-generating apparatus. Which is defined to ensure sonic flow of gas from the first chamber to the second chamber.

The second casing 2A is closed on the outer front end 13 side thereof, and has a metal door 16 on the inner front end 14 side thereof.

The first and second chambers communicate with each other via an intermediate volume defining a third chamber, which communicates with the outside through an aperture formed in the housing.

Advantageously, the first charge placed in the first chamber is a solid propellant and the second composition placed in the second chamber is constituted by a mixture of at least one oxidizing charge and at least one reducing charge. Generally, gas generators used to inflate air bags must be capable of operating for a few milliseconds to a few seconds, depending on the operating requirements of the personal protection air bag system. Preferably, therefore, the first charge is a double-base or composite propellant or a ballistic powder of the Lova type.

The propellant may be in the form of an unconstrained block (block). In this case, the propellant block has radial branches in order to limit the influence of the walls of the first chamber, to increase the charge density and to increase the reaction surface. According to a preferred configuration, the propellant block has a finned annular shape, as shown in fig. 2.

It is also possible to use a bis-based (nitrocellulose/nitroglycerine, preferably without alkaline anti-glare salt) propellant, for example the following:

-SD 1152 propellant, energy: 1000 calories/g; vc: 30 mm/sec, plateau effect at 20MPA, gas production: 1.0/g, no residue

SD1133 propellant (energy: 800 cal/g, Vc at 5.5 MPa: 10 mm/s, gas yield: 1.0/g, no residue).

In both cases, the part of the generator device that contains the leaking first filler must be arranged to allow the gases formed during the aging of the generator to escape.

Silicone-bonded composite propellants may also be used. Advantageously, the silicone-bonded composite propellant used consists of 41% ammonium perchlorate, 36% potassium nitrate, 22% silicone binder, 2% additive (gas yield: 0.7l/g, residue: 0.3g/g) Vc ═ 30 mm/sec at 35 MPa.

Composite propellants with polybutadiene binders may also be used. Advantageously, the composite propellant used with the polybutadiene binder consists of 88% ammonium perchlorate, 14% polybutadiene. (gas yield: 1l/g, 0 residue but HCl to be fixed). Vc at 10 MPa: 1.7 mm/sec.

For the ballistic powder of the Lova type, the composition was 84% trimethylenetrinitramine, 14% Nilpol, 2% additive (burn rate: 20 mm/ms to 25 mm/ms; Lova strand size: height 3.5mm to 4.8 mm; outer diameter 3.5 mm; inner diameter 1.8 mm; gas yield: 1l/g, 0 residue).

Preference is given to using monobasic propellants (monethonic propellant). The advantage of choosing to burn a nozzle controlled monobloc propellant is that the risk of failure of the first charge is reduced. If the components are separated, the matrix retains its integrity without risk of failure of the first filler. Furthermore, the performance is also improved: the flow rate can be adjusted according to the shape and thus a constant flow rate can be achieved; propellants with a temperature coefficient of zero (plateau effect) or less than 0.3 may also be selected; it is also possible to choose to operate the propellant at a pressure of 100 bar to 200 bar at any temperature; the combustion time of the first chamber can also be adjusted from a few milliseconds to a few seconds. Furthermore, they cover a wide range of burning times, operate at moderate pressures (typically <20MPa), and are not very temperature sensitive.

The first charge is a "cold" energy material, i.e., hard to initiate. An igniter charged with 0.04g of potassium perchlorate/zirconium and 0.090g of potassium nitrate/boron was provided. An intermediate charge of about 0.5g of a potassium nitrate/boron composition or a composition of 36% guanidine nitrate, 62% copper oxide 62% and 2% additives was also required.

The second charge is prepared in such a way that: the mixture obtained is homogeneous, has a density of 0.9 ± 0.2, can be poured for filling and is not subject to separation, and the oxygen balance of the gas produced by combustion of the first and second fillings and leaving the generator is between-5% and + 1%.

"oxygen balance" is defined as the mass number of oxygen supplied or consumed per 100g of compound. When all the oxygen in the oxidant is consumed by the reductant, the oxygen balance is zero.

For this purpose, the second charge is advantageously prepared by co-grinding the components whose particle size has been previously adjusted using a ball mill.

For the treatment of 400g to 500g of one or more components, the ball mill consists of a 5 liter ceramic pot with a ratio H/D of 1 and 4Kg of ceramic balls with a diameter of 10mm to 30 mm. The can was rotated horizontally at 100rpm for a determined period of time. The co-milling technique has the advantage of being easily adaptable to large-scale continuous production by using so-called single-screw or twin-screw systems.

The co-milling technique of the mixture is advantageous in that it allows the two components to agglomerate in a single form. The resulting mixture is homogeneous, without "fines", because the applied co-milling agglomerates the component particles without classifying them, and thus the particle size is compacted. Advantageously, a second filler is required consisting of particles (granules) with a constant size. By constant particle size composition is meant a composition comprising at least 95% of such particles which are ± 10% identical in cross section. Advantageously, particles with a cross section in the range of 30 μm to ± 10% are sought.

The following is an example of preparing the second filler by co-grinding. In these examples, the nominal composition of the second charge is adjusted according to the first charge to obtain the oxygen balance (-5% to + 1%) of the specified explosive charge and to fix undesired substances, such as hydrochloric acid, nitrogen oxides in the case of composite propellants. Other additives, such as diluents, may be added. Furthermore, all operations were performed at a controlled humidity of 25% ± 5%. All devices in contact with the powder composition were pre-dried at 70 ℃ for 12 hours ± 2 hours.

Example 1(Riegel)

The second charge consisted of 57% ammonium nitrate and 43% guanidine nitrate.

Since the explosive charge is balanced, the composition evolves according to the nature and mass of the first compound and the oxygen balance chosen (e.g., NA: 84%, GuNi: 16%).

The components were prepared as follows:

ammonium nitrate of NAEO quality was obtained by spraying a 90% concentrated solution of ammonium nitrate in a "prilling" tower (supplier: la Grande Paroisse). The product presents compact grains with the diameter of 1mm and has high mechanical resistance. Is porous and is not affected by crystallographic changes. The density of which is about 0.7g/cm³. It is ground separately (ball mill, speed 100rpm, duration 15 minutes) to obtain a particle size advantageously of about 30 μm.

Guanidine nitrate (supplier: Degusa) having a particle size of 300 μm was ground alone (ball milled for 30 minutes at 100 rpm) to advantageously achieve a particle size of about 30 μm.

Once the ammonium nitrate and guanidine nitrate have been ground, both compounds are introduced into the grinding tank along with the balls for a co-grinding operation. (tank: 5 l H/D1, balls: 4Kg balls with a diameter of 10mm to 30mm, as described above, for 4g to 500g of the mixture to be treated). The jar was rotated horizontally at 100rpm for one minute. This time has been determined to agglomerate the grains, and very short operations do not allow significant changes in the particle size of the components. The resulting mixture had an apparent density of 0.76g/cm³(29cm³Middle 22g Riegel). Riegel and its derivatives were classified as 1.3 b: "materials that burn relatively slowly and have minimal impact from explosions and sprays".

Of course, this is one example of manufacturing Riegel, and other techniques may be used, such as the following: the mixture is dissolved and the solution is evaporated according to the method of manufacturing pellets or granules, and then, if necessary, the mixture is ground to obtain a second filler having a particle size distribution of about 30 μm and an apparent density of 0.7 to 1.1.

The innovation is characterized by the development and use mode of the material: they are powders uniformly distributed in the cartridge. These characteristics are not affected by operational aging. Riegel has an apparent density of 7.5 and its solid component has apparent densities of 1.44 and 1.70; the apparent density of the powder state is variable but is usually less than 7. This process stabilizes the shape of the mixture.

Example 2(Vega)

The second charge consisted of 40% nitroguanidine and 60% ammonium nitrate.

Ammonium nitrate of NAEO quality was obtained by spraying a 90% concentrated solution of ammonium nitrate into a "prilling" tower as in example 1 (supplier: Great Parish). The product exhibits dense grains of 1mm diameter with high mechanical resistance. Is porous and is not affected by crystallographic changes. The density of which is about 0.7g/cm³. It was separately milled (speed 100rpm for 15 minutes) to obtain a particle size of about 30 μm.

Nitroguanidine, having a particle size of 125 μm, was ground for 30 minutes to reach a particle size of about 30 μm.

Once the ammonium nitrate and nitroguanidine have been milled, as in example 1, the two compounds are introduced into the milling tank along with the balls for the co-milling operation. The jar was rotated horizontally at 100rpm for one minute.

Of course, this is one example of manufacturing Vega, and other techniques may be used, such as the following: the mixture is dissolved according to the pelletizing or granulating method, the solution is evaporated and then the mixture is ground to obtain a second charge with a particle size distribution of around 30 μm.

Example 3(Mercure)

The second charge consisted of 48.5% basic copper nitrate and 51.5% guanidine nitrate.

As in the previous examples, the two compounds were introduced into the milling tank along with the balls for the co-milling operation. The jar was rotated horizontally at 100rpm for one minute.

When the composition comprises less than 2% of an additive of fumed silica or of boric acid type, it is added and mixed with the two compounds which have previously undergone a co-grinding step. The mixing operation was carried out in a mill with no added balls.

An oxidizer, such as potassium nitrate or sodium nitrate, is added to the ammonium nitrate, if necessary, first ground, then co-ground with the ammonium nitrate, and then co-ground with the reductant. This applies to the reducing additive.

The preparation of the second filler is of course not limited to the co-grinding technique and other mixing techniques may be used without departing from the scope of the invention. These may include, for example, gravity mixing, grinding in a mortar, grinding with a ball mill, in order to obtain a defined particle size of preferably about 30 μm.

Regardless of the composition of the second charge, the gravity homogenization step is carried out in a homogenization cylinder, advantageously by impact by dropping a small mass of material on a piston in contact with the powder. Vibration or vertical impact operations may also be performed. In the latter case, the cartridge is attached vertically to a cylinder that lifts it up and down. To obtain a satisfactory homogenization, about 200 impacts are performed within 2 minutes. This operation does not take place by compression.

The loading of the second filling into the relative cartridge is carried out with HR < 25%.

The density of the powder charged into the second chamber is advantageously 9g/cm³±2g/cm³. Depending on the nature of the components, their method of preparation and the method of preparation of the mixture. The density is reproducible according to the formulation and method selected. The mass of the mixture and the volume of the cartridge were fixed as confirmed at the time of filling.

Once filling is complete, sealing measures (. gtoreq.1.10) by welding and subsequent penetrants^-7Mbar.l/sec, i.e. 1.10^-9Pa·m³Second) closed cartridge/second chamber.

The door seal is specific to each configuration. Which may be obtained using a lid or by inducing a rupture on the second chamber. The ignition relay may be glued to the cover to facilitate opening. In this case, a zirconia copper composition is preferred.

The innovation is characterized by the development and use mode of the material: they are powders uniformly distributed in the cartridge. These characteristics are not affected by operational aging. The method stabilizes the shape of the mixture.

Since the combustion is not autonomous but controlled by the first charge, the reaction is made to proceed at a low pressure to ensure a safe gas generating apparatus.

Such second filler compositions are advantageous in that they stabilize the performance of the gas generating apparatus since the powder state of the second filler does not change with time. Furthermore, the formulation shown allows to adjust the composition of the gas formed by the explosive (first/second) filler. Finally, the volume of gas produced can be in the range of 0.1 moles to 0.4 moles and further ranges.

Advantageously, the first charge/explosive charge mass ratio is between 12% and 30%, preferably between 15% and 25%, the oxygen balance of the gas leaving the generator having to be between-5% and + 1%. The oxygen balance is defined as the mass number of oxygen provided or consumed per 100g of compound. When all the oxygen in the oxidant is consumed by the reductant, the oxygen balance is zero.

The following table lists the characteristics of the gas generator 10 and the composition of the first and second charges contained therein.

Gas generator with LOVA

The pressure in chamber 1 and chamber 2 is high.

TABLE 1

First filler 1	Lova mass 3.20g
		Initiator15	Patvag
Intermediate filler	0.55g BNP +0.1g thermofuse
		Nozzle diameter
12	1.7mm
		Distance X between nozzle and door	16mm
Second filler 2	Riegel 20.8g
		Permeability of door 16	47％(258mm²)
Escape surface	160mm²

As a result: a chamber 155 MPa; chamber 214 MPa 2MPa, in a 60l tank under nitrogen, the generator produced Pmax of 0.34MPa 0.2MPa for a duration of 31 ms 2 ms.

Due to the selection of the LOVA, the pressure in the first chamber (55MPa) and chamber 2(14MPa) is relatively high. An operating time of about 30 milliseconds is still associated with vehicle safety applications.

In the case of a gas generating device for inflating a 16-liter knee protection bag, the characteristics of such a device and the composition of the first and second fillers contained therein are listed in the following two tables.

TABLE 2

First filler 1	Lova mass 1.22g
		Initiator
15	Indet
		Intermediate filler	0.15g BNP
Nozzle diameter
	12	1.5mm
Distance X between nozzle and door			5.5mm
	Second filler 2	Riegel 5.5g
Permeability of door			40％(134mm²)
	Escape surface	55mm²

As a result: 153 MPa in the chamber; chamber 216 MPa. + -. 2MPa, in a 60l tank under nitrogen, the generator produced Pmax of 0.26 MPa. + -. 0.2MPa for a duration of 31 ms. + -. 2 ms.

Here again, the selection of Lova will result in a pressure of 16MPa in the second chamber.

With regard to the shape and characteristics of the cartridge, an aspect ratio of 0.5 to 2.2 is advantageously defined to allow the second charge to burn regularly and completely. It is also defined for the door or washer that its free surface should be 1.5 times the discharge surface, i.e. for 542mm²Has a solid surface of 210mm²To 315mm²The discharge surface of the discharge port of the third chamber was 140mm²To 210mm²。

The following two tables detail the characteristics of 1.6g Lova and 16g Riegel loaded gas generators with L/D ratios of 0.88 to 2.

TABLE 3

First filler 1	Lova mass 1.60g
		Initiator
15	Patvag
		Intermediate filler	0.15g BNP
Nozzle diameter
	12	1.6mm
Distance X between nozzle and door			4mm
	Second filler
2		Riegel 16g
	Permeability of door		47％(258mm²)
Escape surface		160mm²

TABLE 4

TFP, time to first pressure, delay of tank pressure 0.015Pmax

Gas generator with double-base propellant

Further examples of generator devices are given below (fig. 3 and 4).

Effect of particle size on gas Generator set filled with SD1152 and Vega propellants

The following two tables show in detail the characteristics of a gas generator filled with 3.70g of SD1152 propellant and 20g of Vega, whose ammonium nitrate has a particle size strictly greater than 100 μm and strictly less than 500 μm (without fines) (NiGu filtered at 125 μm, mixing based on gravity). The pressure in the chamber 2 is therefore less than 10 MPa.

TABLE 5

First filler	Weight of bis 1152.70 g
		Initiator	Davey Bickford
Intermediate filler	0.30g BNP
		Diameter of nozzle	3.5mm
Distance X between nozzle and door	33mm
		Second filler	Vega 20.0g
Permeability of door	47％
		Escape surface	174mm²

TABLE 6

The absence of fine particles stabilizes the combustion of the filler 2. In the same configuration, we show a proportionality between the pressure in the tank and the mass of the filler 2 in the range 18g to 22 g.

The following table shows the effect of inverting chambers 2 and 3 (the downstream configuration shown in fig. 4).

TABLE 7

First filler	Weight of bis 1152.10 g
		Initiator	Patvag
Intermediate filler	0.50g Zr/CuO
		Diameter of nozzle	2.4mm
Distance X between nozzle and door	0mm
		Second filler	Vega 12g
Permeability of door	47％
		Escape surface	143mm²

As a result: a chamber 133 MPa; the chamber 29 MPa, in a 60l tank under nitrogen, the generator generates Pmax at 0.21MPa for a duration of 30 milliseconds.

₃Composite preforms filled with silicone S1 adhesive (42% AP; 35% KNO; 21% silicone adhesive) The ratio of propellant gas generator to propellant gas generator filled with 1152 propellant, Vega as the second filler Then the obtained product is obtained.

The following two tables detail the characteristics of the gas generator device filled with 3.30g of composite propellant and 3.35g of SD1152, as well as the pressure and operating time within the resulting device chamber.

TABLE 8

First filler	Weight of the biradical 1152 is 3.7g, weight of S1 is: 3.35g
		Initiator	Patvag
Intermediate filler	0.3g BNP
		Diameter of nozzle	3.5mm
Distance X between nozzle and door	33mm
		Second filler	Vega 20.0g
Permeability of door	47％
		Escape surface	174mm²

TABLE 9

Generally, the gas generating devices tested with the three types of propellants (LOVA, SD1152 and SD1152+ SI) had the same performance.

Examples of Mercury composition-filled gas Generator

The following two tables detail the characteristics of the gas-generating apparatus so charged and the pressures and operating times obtained in the apparatus chamber.

Watch 10

First filler	Weight of bis 1152 g
		Initiator	Patvag
Intermediate filler	0.3g BNP
		Diameter of nozzle	3.5mm
Nozzle-door distance X	33mm
		Second filler	Mercury 25g
Permeability of door	47％
		Escape surface	174mm²

TABLE 11

The examples provided do not show the goal of the pressure in the second chamber being less than 10 MPa.

Example of a gas generating device filled with SD1152 propellant and having an increased second charge

The following two tables detail the characteristics of the gas generator device and the resulting pressure and operating time within the device chamber.

TABLE 12

First filler	Weight of the bis 1152 g
		Initiator	DB
Intermediate filler	0.3g BNP
		Diameter of nozzle	5.1mm
Distance X between nozzle and door	33mm
		Second filler	16NA +4g GuNi) mixture
Permeability of door	50％
		Escape surface	291mm²

Watch 13

In the previous examples, we have shown a duration of tens of milliseconds with a suitable propellant, which can extend to hundreds of seconds or even seconds.

Gas generator filled with a second filler mixture of dual base 1133 propellant and 14 NA +2.6g NiGu Examples of (2)

The following two tables detail the characteristics of the permanent gas generator device so loaded and the resulting pressure and operating time within the device chamber. Mixture of second fillers (14g NA or 84% and 2.6NiGu or 16%).

TABLE 14

First filler	Biradical 1133 weighed 6.45g
		Initiator	DB
Intermediate filler	0.40g BNP
		Distance X between nozzle and door	30mm
Diameter of nozzle	2.6mm
		Second filler	14g NA +2.6g NiGu mixture
Escape surface	64mm²
		Permeability of door	50％

Watch 15

Examples of very durable gas generators filled with Butalite and Riel

The following two tables detail the characteristics of the gas-generating apparatus so loaded, as well as the pressures and operating times obtained within the apparatus chamber. The Riegel mixture was prepared using a pelletizing method by dissolving the components and allowing them to evaporate. The result is a sphere of diameter 1 mm. + -. 0.5mm used as such. The pressure value selected for Butalite is in the range of 6MPa to 10MPa, and the burning rate is 1.7 mm.

TABLE 16

First filler	Butalite C1559-2 mass 16g
		Initiator	Patvag
Intermediate filler	0.5g ZrCuO
		Diameter of nozzle	1.13mm
Distance X between nozzle and door	7.9
		Second filler	Riegel Mix b 89g
Escape surface	30mm²
		Permeability of door	30％

TABLE 17

The invention has been described above by way of example. It is to be understood that those skilled in the art can implement various embodiments of the invention without departing from the scope of the invention.

Claims

1. A gas-generating device for inflating an airbag, consisting of a first chamber containing a first pyrotechnic composition and a second chamber containing a second composition, the first and second chambers being in communication with each other, the first composition being a solid propellant capable of controlling the second composition consisting of a mixture of at least one oxidizing filler and at least one reducing filler, the first chamber being formed in a first casing resistant to a given operating pressure of the first pyrotechnic composition, the second chamber being formed in a second casing resistant to a given lower operating pressure of the second composition, the first and second casings being located in an outer casing, the second casing having at one end a metal door defining a volume in communication with the outside through at least one gas escape opening formed in the outer casing, is characterized in that: the second composition is a powder mixture of at least two components, the first component being ammonium perchlorate, ammonium nitrate, potassium nitrate or basic copper nitrate and the second component being a carbon-hydrogen-oxygen-nitrogen reducing derivative derived from an amino derivative or a nitrate derivative of guanidine, oxamide, urea, triazole, tetrazole, the powder mixture being formed from particles having a particle size greater than or equal to 20 μm and a bulk density of from 0.7 to 1.1.

2. Gas generating device according to claim 1, characterized in that the powder mixture is formed by particles with a particle size of 20 μm to 100 μm, preferably 20 μm to 60 μm, and preferably 30 μm.

3. A gas-generating apparatus according to claim 1 or claim 2, characterised in that the mixture is a eutectic.

4. Gas generating device according to any of the preceding claims, characterized in that the powder mixture is co-ground.

5. Gas-generating device according to any one of the preceding claims, characterized in that the second composition is adjusted so that the oxygen balance of the gas produced by the reaction of the first and second compositions at the outlet of the generating device is greater than-5%, advantageously from-5% to + 1%, and preferably from-3% to + 1%.

6. Gas-generating device according to any one of the preceding claims, characterized in that the first housing of the first chamber withstands an operating pressure of more than 5 MPa.

7. Gas-generating device according to any one of the preceding claims, characterized in that the first housing of the second chamber withstands an operating pressure of less than 15 MPa.

8. Gas-generating device according to any one of the preceding claims, characterized in that the second housing of the second chamber withstands an operating pressure of more than 3 MPa.

9. Gas-generating device according to any one of the preceding claims, characterized in that the second housing of the second chamber withstands an operating pressure of less than 30 MPa.

10. Gas-generating device according to any one of the preceding claims, characterized in that the operating pressure of the second chamber is less than 15MPa (150 bar), preferably less than 10MPa (100 bar), and advantageously less than 5 MPa.

11. Gas-generating device according to any one of the preceding claims, characterized in that the volume of gas generated by the second chamber covers a range from 0.25 mol to more than 4 mol.

12. Gas-generating device according to any one of the preceding claims, characterized in that the second composition consists of guanidine nitrate and ammonium nitrate.

13. Gas generating device according to any of the preceding claims, characterized in that the second composition consists of guanidine nitrate and basic copper nitrate.

14. Gas generating device according to any of the preceding claims, characterized in that the first housing comprises at least one initiator which can be activated by external control equipped with reinforcing and intermediate charges.

15. A gas-generating apparatus according to any of the preceding claims, characterized in that the first charge is a propellant having an operating pressure of less than 30MPa and a burning time in the range of 0.015 seconds to 2.5 seconds.

16. Gas generating device according to any of the preceding claims, characterized in that the door has one or more holes defining a surface that is more permeable than the gas escape opening.

17. A gas-generating device according to any one of the preceding claims, characterized in that the first chamber communicates with the second chamber via a nozzle defined to ensure a sonic flow of gas from the first chamber to the second chamber.

18. Gas-generating device according to the preceding claim, characterized in that said nozzle and said door are arranged at a distance of less than 40mm from each other.