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WO2025051596A1 - Élément combustible pour générateur de gaz, son procédé de production et son utilisation - Google Patents

Élément combustible pour générateur de gaz, son procédé de production et son utilisation Download PDF

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Publication number
WO2025051596A1
WO2025051596A1 PCT/EP2024/073992 EP2024073992W WO2025051596A1 WO 2025051596 A1 WO2025051596 A1 WO 2025051596A1 EP 2024073992 W EP2024073992 W EP 2024073992W WO 2025051596 A1 WO2025051596 A1 WO 2025051596A1
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WO
WIPO (PCT)
Prior art keywords
pyrotechnic
core
ignition agent
tablet
ignition
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/EP2024/073992
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German (de)
English (en)
Inventor
Michael König
Sebastian Wienhold
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ZF Airbag Germany GmbH
Original Assignee
ZF Airbag Germany GmbH
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Filing date
Publication date
Application filed by ZF Airbag Germany GmbH filed Critical ZF Airbag Germany GmbH
Publication of WO2025051596A1 publication Critical patent/WO2025051596A1/fr
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C06—EXPLOSIVES; MATCHES
    • C06D—MEANS FOR GENERATING SMOKE OR MIST; GAS-ATTACK COMPOSITIONS; GENERATION OF GAS FOR BLASTING OR PROPULSION (CHEMICAL PART)
    • C06D5/00—Generation of pressure gas, e.g. for blasting cartridges, starting cartridges, rockets
    • C06D5/06—Generation of pressure gas, e.g. for blasting cartridges, starting cartridges, rockets by reaction of two or more solids
    • C—CHEMISTRY; METALLURGY
    • C06—EXPLOSIVES; MATCHES
    • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
    • C06B45/00—Compositions or products which are defined by structure or arrangement of component of product
    • C06B45/18—Compositions or products which are defined by structure or arrangement of component of product comprising a coated component

Definitions

  • Fuel element for a gas generator Method for its production and use of the fuel element
  • the invention relates to a fuel element for a gas generator for use in a safety device, a method for producing such a fuel element and the use of such a fuel element in a safety device.
  • Fuel elements for gas generators are known from the prior art.
  • various safety devices are provided in vehicles.
  • One such safety device could, for example, be a gas bag module equipped with a gas generator.
  • the gas generator releases a pressurized gas that deploys a gas bag from the gas bag module, thereby restraining the vehicle occupants.
  • Gas generators are used to generate a pressurized gas and are known in various designs. Basically, gas generators use a propellant element made of a pyrotechnic composition, which is located inside the gas generator. When activated by an electrical igniter, it undergoes an exothermic reaction, releasing the pressurized gas in the gas bag.
  • Propellant elements are typically in the form of tablets, which can be manufactured in various ways. These tablets generally have a multi-component structure.
  • propellant elements in the form of tablets are known, which are composed of two or more pyrotechnic components.
  • the integration of various pyrotechnic components or compositions in one tablet serves to specifically influence the combustion characteristics of the propellant element. By optimizing the combustion characteristics, improved inflation behavior of the gas bag can be achieved, among other things.
  • the term "burn-up characteristics" refers to a series of properties that a propellant pellet or propellant element for a gas generator exhibits during operation, i.e., during combustion.
  • Combustion characteristics include, for example, the burn-up rate, the burn-up velocity, the burn-up velocity at the surface, the gas yield, the autoignition temperature, the ignitability, the superignitability, the pressure exponents, and the general burn-up behavior (degressive or progressive).
  • a coated pellet for a gas generator is disclosed in DE 10 2012 024 799 A1.
  • a propellant element is proposed that is designed as a pellet having a core made of a pyrotechnic material, wherein the core is at least partially surrounded by a shell made of a material that delays the combustion of the core.
  • German patent application 10 2022 108 291.1 describes propellant elements in the form of a coated pellet, comprising a core made of a pyrotechnic material and a coating layer surrounding the core made of a second pyrotechnic material different from the first pyrotechnic material.
  • the core extends through the coating layer over a protruding edge portion along a circumferential direction, so that the combustion of the core can occur parallel to the combustion of the coating layer. In this way, undesirable degressive combustion of the coated pellet can be avoided or at least limited, and the ignitability of the coated pellet can be adjusted.
  • propellant elements that ignite reliably even at the lowest possible temperatures and enable rapid pressure buildup are desirable.
  • pyrotechnic compositions with corresponding ignition behavior exhibit an undesirably high combustion temperature, require ignition with hot particles, and/or produce a comparatively high amount of particulate, i.e., solid, combustion products, which adversely affect the smoke development of the gas generator.
  • the object of the invention is to provide a fuel element that ignites even at low temperatures and has a defined combustion characteristic.
  • the object is achieved according to the invention by a fuel element according to claim 1, a method for producing a fuel element according to claim 9 and the use of a fuel element according to claim 10.
  • a propellant element for a gas generator for use in a safety device in the form of a tablet has a core made of pyrotechnic material and a coating of a pyrotechnic pre-ignition agent applied to the core, wherein the pyrotechnic material and the pyrotechnic pre-ignition agent differ from one another.
  • the pyrotechnic pre-ignition agent has a deflagration temperature of 500 K or less.
  • the invention is based on the fundamental idea of improving the ignition behavior of the entire propellant element at low temperatures by using a pyrotechnic pre-ignition agent that has a comparatively low deflagration temperature of 500 K or less for pyrotechnic compositions, thus enabling the targeted adjustment of the combustion characteristics.
  • the low deflagration temperature of the pyrotechnic pre-ignition agent enables the propellant element to ignite particularly reliably and early upon mere temperature increase, without relying on the use of hot particles to activate the propellant element or at least without being able to reduce their quantity.
  • the term "pure temperature increase” means that the temperature increase is achieved through the influence of radiation and/or a gas mixture surrounding the fuel element is heated, and the heat transferred from the gas mixture to the fuel element by means of diffusion and/or convection processes is sufficient to ignite the fuel element, specifically the early ignition layer.
  • hot particles are not used to ignite the early ignition layer.
  • this does not preclude the additional use of hot particles to further influence the ignition behavior of the fuel element, even if this is not preferred.
  • the adjustment options for the ignition behavior and the combustion characteristics of the fuel element are expanded compared to fuel elements known in the prior art, thus increasing the freedom of formulation.
  • the deflagration temperature is a particularly suitable parameter for testing the suitability of a pyrotechnic composition for use as an early ignition layer.
  • This effect is attributed to the fact that, for the same type of components used in the pyrotechnic composition, the proportions of these components can be varied within a wide range without significantly affecting the deflagration temperature.
  • This makes it possible to vary the respective chemical composition of the early ignition layer within a wide range in order to adjust or optimize further parameters of the early ignition layer. that influence the combustion characteristics.
  • the deflagration temperature represents a kind of "early ignition eutectic.”
  • the deflagration temperature of the pyrotechnic material used in the core is above the deflagration temperature of the pre-ignition agent.
  • the improved pre-ignition behavior of the fuel element thus makes it possible to vary the other parameters of the fuel element that influence the combustion characteristics to a greater extent and still achieve improved or similar combustion behavior.
  • the geometry of the pellet can be varied to a greater extent while maintaining comparable combustion characteristics, or it can be maintained while maintaining improved combustion characteristics compared to existing propellant elements.
  • so-called ignition sleeves in the gas generator in which pressure and temperature develop separately from the rest of the gas chamber, can be omitted.
  • the fuel element is in tablet form, it can be produced particularly cost-effectively, for example by a compression process.
  • the geometric shape of the tablet is not further restricted.
  • the tablet has a cylindrical shape.
  • the pyrotechnic pre-ignition agent may have a deflagration temperature of 450 K or less, preferably 435 K or less. This allows the propellant element to be activated at even lower temperatures.
  • the pre-ignition agent may have a deflagration temperature of at least 381.15 K, in particular of at least 403.15 K. Accordingly, the pyrotechnic pre-ignition agent may have a deflagration temperature in the range of 381.15 to 450 K, preferably from 403.15 K to 435 K.
  • the pyrotechnic pre-ignition agent has a combustion temperature of 2000 K or more and preferably a combustion temperature in the range of 2100 K to 2800 K. Lower combustion temperatures can lead to pre-ignition agents that have too low a combustion rate and/or explosion heat, which can delay the ignition of the pyrotechnic material by the triggered pre-ignition layer.
  • the relative arrangement of pyrotechnic pre-ignition agent and pyrotechnic composition within the tablet is in principle not further restricted as long as the desired combustion characteristics can be achieved.
  • the coating of pyrotechnic pre-ignition agent is applied to a top side, a bottom side and/or a shell side of the core.
  • the propellant element can have a contact-enhancing surface design.
  • the core has recesses into which the pyrotechnic pre-ignition agent is incorporated and/or the core has a roughened contact surface that is in contact with the pre-ignition agent. This further improves the transferability of the pyrotechnic pre-ignition agent to the pyrotechnic composition.
  • the layer thickness of the coating of the pyrotechnic pre-ignition agent can be chosen arbitrarily, depending on the desired combustion characteristics of the propellant element.
  • the thickness of the coating of the pyrotechnic pre-ignition agent is 10% or less of the thickness of the tablet. This makes it particularly easy to ensure that the tablet as a whole is ignited by the pyrotechnic pre-ignition agent even at a low temperature. However, the further behavior of the tablet is essentially determined by the pyrotechnic composition of the core.
  • the tablet has several spatially separated areas with the coating of the pyrotechnic pre-ignition agent, the thickness of the part of the coating with the greatest thickness is counted.
  • the thickness of the coating of the pyrotechnic pre-ignition agent is in the range of 0.5 to 3.0 mm.
  • the pyrotechnic pre-ignition agent comprises a fuel as component (A) and an oxidising agent as component (B) and optionally further additives as component (C).
  • the fuel (A) of the pyrotechnic pre-ignition agent is in particular selected from the group consisting of 1-nitroguanidine, guanidinium nitrate, nitrotriazolone, nitrocellulose, metals, in particular boron, aluminum, titanium, zirconium, tungsten, and combinations thereof.
  • the oxidizing agent (B) of the pyrotechnic pre-ignition agent is in particular selected from the group of chlorates, perchlorates, metal oxides, and combinations thereof.
  • the oxidizing agent of the pyrotechnic pre-ignition agent preferably comprises or consists of potassium perchlorate.
  • the pyrotechnic pre-ignition agent comprises the following components:
  • oxidizing agent selected from the group of chlorates, perchlorates, metal oxides and combinations thereof, preferably potassium perchlorate
  • the core can have a first core region made of a first pyrotechnic material and a second core region made of a second pyrotechnic material, wherein the first pyrotechnic material and the second pyrotechnic material differ from each other.
  • the combustion characteristics of the propellant element can be influenced by the choice of the first and second pyrotechnic materials in addition to the selected coating of the pyrotechnic pre-ignition agent.
  • the two pyrotechnic materials i.e., the first pyrotechnic material and the second pyrotechnic material, differ in particular with respect to at least one of the following properties: chemical composition, combustion rate, combustion temperature, gas yield, average grain size, particle distribution, particle morphology, hygroscopicity, autoignition temperature, ignitability, deflagration temperature, and overignitability.
  • the two pyrotechnic materials may also differ in two or more of the aforementioned properties.
  • the deflagration temperature of both the first pyrotechnic material and the second pyrotechnic material is above the deflagration temperature of the pyrotechnic pre-ignition agent.
  • the first pyrotechnic material has a higher burning rate than the second pyrotechnic material.
  • the first pyrotechnic material may have a burning rate in a range of 20 to 60 mm/s at 20 MPa, preferably 25 to 55 mm/s at 20 MPa
  • the second pyrotechnic material has a burning rate in a range of 5 to 30 mm/s at 20 MPa, preferably 15 to 25 mm/s at 20 MPa. In this way, a degressive burning of the first core region can be avoided, thereby achieving an even more uniform burning of the tablet.
  • the first pyrotechnic material has a grain size which differs from the grain size of the second pyrotechnic material, wherein in particular the first pyrotechnic material has an average grain size (D50) in a range from 1 to 30 pm and the second pyrotechnic material has an average grain size (D50) in a range from 3 to 100 pm.
  • the first pyrotechnic material and the second pyrotechnic material each comprise at least a fuel and an oxidizer.
  • the invention is not limited with respect to the fuel and oxidizer of the first and second pyrotechnic materials. Any fuel and oxidizer known in the art that are suitable for forming a propellant element for a gas generator can be used.
  • the fuel of the first and/or second pyrotechnic material is selected from the group consisting of guanidinium salts, aluminum, polyvinyl acetate, 1-nitroguanidine, nitrotriazolone, tetrazoles, bitetrazoles and nitrocellulose and combinations thereof.
  • Such fuels can generate a large gas volume upon activation and enable pyrotechnic compositions in which the burning rate can be adjusted over a wide range.
  • the oxidizing agent of the first and/or second pyrotechnic material is selected, in particular, from the group consisting of perchlorates, copper oxide, basic copper nitrate, basic copper zinc nitrate, sodium nitrate, potassium nitrate, and combinations thereof.
  • the oxidizing agent serves, in particular, to increase the burning rate of the respective pyrotechnic material.
  • the burning rate of the propellant element can therefore be influenced.
  • the first and second pyrotechnic materials can each contain at least one further additive, which is in particular selected from the group consisting of stabilizers, burn rate modifiers, binders, compression additives, and combinations thereof.
  • the properties of the propellant element can be modified by adding one of the above-mentioned additives.
  • iron(II) oxide magnesium oxide, titanium oxide, aluminum oxide and combinations thereof can be used as burn rate modifiers.
  • amorphous silica, calcium stearate and hydrocarbon-based lubricating oil preferably lubricating oil based on aliphatic hydrocarbon compounds having 15 to 30 carbon atoms, as well as combinations thereof, can be used as pressing additives.
  • Akardit II (3-methyl-1,1-diphenylurea) can be used as a stabilizer.
  • Binders that can be used include, for example, alkylcelluloses, hydroxyalkylcelluloses, carboxymethylcelluloses, cellulose carboxylates, xanthan, hydroxyl-terminated polybutadiene (HTPB) and carboxyl-terminated polybutadiene (CTPB) and combinations thereof.
  • the chemical compositions of the first and second pyrotechnic materials differ from each other.
  • the first pyrotechnic material and the second pyrotechnic material differ in the selection of at least one of the components such as fuel, oxidizer and an additive.
  • the first and second pyrotechnic materials can also be based on the same components, but differ in their component proportions. This can also alter the combustion characteristics.
  • the first pyrotechnic material can have a higher proportion of oxidizer, which can lead to an increased combustion rate compared to the second pyrotechnic material.
  • the first pyrotechnic material comprises the following components:
  • the second pyrotechnic material comprises the following components:
  • (C) 0 to 15 wt.%, preferably 0 to 5 wt.%, of further additives selected from the group consisting of iron oxide, titanium oxide, Aluminum oxide, calcium stearate, other stearate salts, fatty acid salts and combinations thereof, each based on the total weight of the second core region, wherein the proportions of components (A) to (C) add up to 100 percent by weight.
  • the tablet can be a jacketed tablet in which the first core region is at least partially provided with a casing which is formed by the second core region and/or the coating of the pyrotechnic pre-ignition agent, wherein the first core region has an edge section which projects in the radial direction and extends through the casing to an outer contour of the jacketed tablet, wherein the edge section is formed along a circumferential direction of the jacketed tablet and has a smaller extent in the axial direction of the jacketed tablet than the first core region.
  • the casing can be designed analogously to the shell region of the shell-shaped pellet described in German patent application 10 2022 108 291.1.
  • the coating of the pyrotechnic pre-ignition agent is either a component of the casing or is provided in addition to a casing made of a second pyrotechnic material. In this way, the pre-ignition behavior of the propellant element according to the invention is further improved.
  • an opening in the form of a gap is provided in the casing, which connects the first core region to the outer contour of the coated tablet via the edge section.
  • the edge section having a smaller extent in the axial direction of the coated tablet than the first core region. The presence of an edge section therefore ensures that the combustion of the first core region takes place essentially parallel to the combustion of the casing, but is nevertheless delayed by the geometric design of the tablet, whereby undesirable degressive combustion of the tablet can be prevented.
  • the ignitability of the coated tablet according to the invention can be specifically adjusted in this way. This can be achieved by selecting the axial extent of the gap, which changes the accessibility of the first core region in the form of the edge section. Choosing a larger gap allows more of the edge section and thus a larger part of the core to be made accessible for ignition, whereas a smaller axial extent of the gap has the opposite effect and reduces the ignitability of the first core region.
  • This advantageous control of the properties is not limited to the above-mentioned example of ignitability, but also generally applies to other combustion characteristics such as the degressivity of combustion.
  • the coated tablet proposed here can thus be understood as a hybrid form between known coated tablets and multilayer tablets.
  • the autoignition temperature of the first pyrotechnic material is lower than that of the second pyrotechnic material, an improved early ignition function can be enabled by the exposed web.
  • the geometric design of the proposed coated pellet can achieve improved control over the combustion characteristics.
  • compositions of the first and second pyrotechnic materials are particularly suitable for use in a coated tablet for a gas generator.
  • the composition of the first pyrotechnic material exhibits a faster burning rate than the composition of the second pyrotechnic material.
  • a tablet containing the above-mentioned compositions exhibits, in particular, a reduced degressivity of burning.
  • a web section can be arranged between the tablet top and the tablet bottom, which runs as a band-shaped boundary ring around the tablet and limits the first core region in its radial extent.
  • the web section is retained in its shape by a die wall during compression.
  • the height of the web section can be chosen arbitrarily and limits the axial extent of the edge section of the first core area. However, there can also be two webs that limit the axial extent of the edge section of the core on both sides.
  • the top and bottom of the tablet may be curved or faceted.
  • a curved tablet has a biconvex shape.
  • the top and bottom of the tablet form, in particular, spherical caps.
  • the curvature has a radius of curvature, which represents the radius of the spherical cap.
  • the tablet according to the invention can have a coating.
  • the invention is not restricted with regard to the coating.
  • the coating can be of any shape.
  • the coating forms, in particular, the outer contour of the coated tablet, with the exception of the edge portion that extends through it. Therefore, the coating can also encompass the web as well as the top and bottom of the tablet.
  • the coating thickness can also be freely selected. Depending on the layer thickness selected, the burning characteristics of the tablet can be influenced.
  • the sheathing completely surrounds the core, with the exception of the edge section.
  • the positioning of the edge section relative to the core is arbitrary.
  • the edge section can be positioned centrally or slightly offset from the core.
  • multiple edge sections can also be provided. These can, in particular, run parallel to one another or intersect.
  • the axial extent of the edge section is also arbitrary as long as the axial extent of the edge section is lower than that of the first core area.
  • the axial extent of the edge portion may be at most 80% of the axial extent of the first core region, preferably 60%, more preferably 40%, most preferably 10%.
  • the edge section may preferably have an extension of 100 to 3000 pm in the axial direction, preferably of 100 to 800 pm.
  • the burning characteristics of the tablet can be further influenced by the axial extension of the edge section.
  • the core with the edge section has a shape that can be produced by compression.
  • first core region with the edge portion has a T-shaped cross-section. This offers the advantage that such a shaped first core region with edge portion can be manufactured particularly easily.
  • the first core region with the edge portion has a wedge-shaped cross section.
  • the first core region with the edge portion is convexly shaped, more preferably the first core region with the edge portion is biconvexly shaped.
  • the tablet can be provided with an additional coating on at least one of its end faces and/or the shell sides.
  • This additional coating can provide additional tablet functionality. If a tablet with a coating interrupted by the edge section is used, it is advantageous to apply the additional coating to one of the end faces, as this way the edge section is not covered by the additional coating. This ensures that accessibility to the first core area is not compromised.
  • the additional coating covers the entire tablet, i.e. is arranged on the shell sides as well as the end faces, or that only the shell sides are provided with the additional coating.
  • Hydrophobic polymers in particular silicones, polyurethanes and/or polyesters, can be used as moisture protection coatings.
  • the additional coating may further comprise an ignition layer, which also improves the ignitability of the propellant element, but differs from the pyrotechnic pre-ignition layer, in particular chemically.
  • the ignition layer has a higher deflagration temperature than the coating made of the pyrotechnic pre-ignition agent.
  • the object is also achieved according to the invention by a method for producing a propellant element as described above, wherein the pyrotechnic material and/or the pyrotechnic pre-ignition agent are pressed in a press die to form the core of pyrotechnic material or the coating of the pyrotechnic pre-ignition agent.
  • the process according to the invention enables the production of the tablet according to the invention using compression machines.
  • the production of tablets using compression machines is known and has been used for a long time in the pharmaceutical industry.
  • the process according to the invention Fuel element and the process for producing the fuel element are particularly cost-effective.
  • the components of the propellant element are joined together to form the propellant element exclusively by compression. This avoids the costly coating or lamination of the pre-ignition layer onto the pyrotechnic material of the core, or vice versa.
  • the invention relates to the use of a fuel element as described above in a safety device in a vehicle, in particular in a gas generator.
  • FIG. 15 schematically shows a sequence of a first embodiment of a method according to the invention for producing the fuel element according to the invention
  • FIG. 16 schematically shows a sequence of a second embodiment of the method according to the invention for producing the fuel element according to the invention.
  • a propellant element 10 according to the invention for a gas generator for use in a safety device is in the form of a tablet which a core 12 made of pyrotechnic material and a coating 14 made of a pyrotechnic pre-ignition agent applied to the core 12 (cf. Fig. 3).
  • the pyrotechnic material and the pyrotechnic pre-ignition agent differ from each other, particularly with regard to their deflagration temperature.
  • the pyrotechnic pre-ignition agent has a deflagration temperature of 500 K or less, so that, according to the invention, the pyrotechnic pre-ignition agent can be activated at a lower temperature than the pyrotechnic material.
  • Tables 1 to 3 show exemplary compositions which are suitable as pyrotechnic material in the core 12 of a propellant element 10 according to the invention or as pyrotechnic pre-ignition agent in the coating 14 applied to the core 12.
  • GuNi Guanidinium nitrate
  • PVA polyvinyl acetate
  • Table 4 lists the ballistic properties of the respective compositions.
  • the pyrotechnic material is further differentiated into a first pyrotechnic material and a second pyrotechnic material, which in terms of their respective ballistic properties and thus in their combustion characteristics.
  • the core 12 of the propellant element 10 can have a first core region 15 made of the first pyrotechnic material and a second core region 16 made of the second pyrotechnic material.
  • both the first pyrotechnic material and the second pyrotechnic material can also be present as the only pyrotechnic material in the core 12.
  • Table 4 shows that the first pyrotechnic material (Examples A to D) and the second pyrotechnic material (Examples E to H) differ significantly in their ballistic properties.
  • the first pyrotechnic material exhibits a higher combustion temperature, a higher to comparable combustion rate at a pressure of 5 MPa, a higher combustion rate at a pressure of 20 MPa, a higher to comparable deflagration temperature, and a higher explosion heat than the second pyrotechnic material. Accordingly, the combustion characteristics of a propellant element can be adjusted to a large extent by selecting the pyrotechnic material used or a combination of the various pyrotechnic materials.
  • the pyrotechnic pre-ignition agents (Examples I and J) have a significantly lower deflagration temperature of less than 500 K, namely 433 K, compared to the other pyrotechnic compositions of Examples A to H.
  • Other ballistic properties can be varied within a wide range without any significant change in the deflagration temperature.
  • Table 1 First pyrotechnic compositions.
  • Table 3 Pyrotechnic pre-ignition agents.
  • Table 4 Ballistic properties of the compositions according to Tables 1 to 3.
  • Table 5 Test data on pressure build-up in the standard combustion chamber.
  • the first pyrotechnic material according to Example A was used as propellant 1
  • the second pyrotechnic material according to Example G was used as propellant 2
  • the pre-ignition agent according to Example I was used as pre-ignition agent.
  • a "standard combustion chamber” is a sealed vessel with a defined volume of 100 cm3 in which the respective propellant is burned.
  • the pressure/time curves resulting from combustion characterize the respective composition ballistically.
  • Table 5 lists the tsobar values obtained in each case, i.e., the time required to reach a pressure of 50 bar (5 MPa) in the standard combustion chamber.
  • a low tsobar value is desirable to enable rapid pressure buildup in a gas generator.
  • the tablets presented were ignited by means of a booster charge, which in turn was activated by an electrically ignited igniter.
  • the igniter contained an igniter composition of 53 to 58 wt% zirconium as fuel, 34 to 42 wt% potassium perchlorate as oxidizer and 4 to 5 wt% fluororubber (FKM) as binder.
  • booster charges either a "particle-generating” booster charge or a "gas-generating” booster charge was used to investigate the ballistic behavior of the respective propellant element to be characterized as a function of the type of ignition.
  • the behavior with a gas-generating booster charge corresponds to a case in which the respective pyrotechnic composition essentially only needs to ignite via the temperature increase, since there are no or at least significantly smaller amounts of hot particles that could support the ignition.
  • the particle-generating booster charge comprised 27 to 33 wt% boron as fuel and 67 to 73 wt% potassium nitrate as oxidizer.
  • the gas-generating booster charge comprised 96 wt% nitrocellulose as fuel, 1 to 3 wt% 3-methyl-1,1-diphenylurea as stabilizer, and 0 to 2 wt% disodium oxalate and 0 to 2 wt% graphite as burn rate modifier.
  • Fig. 1 shows pressure/time curves for individual components as they can be used in a fuel element 10 according to the invention, in each case when ignited with a particle-generating booster charge and when ignited with a gas-generating booster charge.
  • Curves 18 and 20 show the behavior of a first pyrotechnic composition, i.e., a composition characterized in particular by a high burning rate, a high burning temperature, and a high heat of explosion. As can be seen, such a composition exhibits the fastest pressure buildup when activated by a particle-generating booster charge, but this is significantly delayed when a gas-generating booster charge is used.
  • Curves 22 and 24 show the behavior of a second pyrotechnic composition, i.e., a composition characterized by a low combustion rate, a low combustion temperature, and a low explosion heat.
  • This composition exhibits both a significantly delayed pressure buildup and a significantly lower maximum pressure than for the first pyrotechnic composition. composition is the case. When using a gas-generating booster charge, the pressure build-up is delayed even further.
  • Curves 26 and 28 represent the behavior of a pyrotechnic pre-ignition agent characterized by a low deflagration temperature. As can be seen in Fig. 1, the pre-ignition agent almost achieves the behavior of the first pyrotechnic composition when using a particle-generating booster charge. However, when using a gas-generating booster charge, the pre-ignition agent exhibits by far the fastest pressure buildup and the highest maximum pressure of the tested examples.
  • the pre-ignition agent is particularly suitable for improving the ignition behavior of a fuel element if hot particles are not to be used to activate the fuel element.
  • Fig. 2 shows additional pressure/time curves demonstrating the behavior of bilayer pellets.
  • a first bilayer pellet with a first layer of "propellant 1" and a second layer of "propellant 2" was tested, while a second bilayer pellet with a first layer of "propellant 2" and a second layer of the pre-ignition agent was tested.
  • curves 18 and 20 are also shown in Fig. 2.
  • Curves 30 and 32 show the behavior of the first bilayer pellet when using a particle-generating and a gas-generating booster charge, respectively. Both the pressure buildup and the maximum pressure are significantly reduced compared to a pellet containing only propellant 1 due to the less ignitable propellant 2, especially in the case of the gas-generating booster charge.
  • the second bi-layer tablet which uses the pyrotechnic pre-ignition agent, exhibits a faster pressure build-up for both the particle-generating and the gas-generating booster charge than is the case for the first bi-layer tablet, particularly in the case of the gas-generating booster charge.
  • propellant elements 10 with different structures are also within the meaning of the invention, in particular those that have combinations of the layer structures shown in Figs. 3 and 14 and/or in which the respective first pyrotechnic material used is replaced by a second pyrotechnic material, and vice versa.
  • a first embodiment of the propellant element 10 is shown, in which the propellant element 10 has a core 12 which is formed only from a single pyrotechnic material, in this case from the first pyrotechnic material.
  • the coating 14 of the pyrotechnic pre-ignition agent is applied to an upper side 38 of the core 12, while a lower side 39 of the core 12 opposite the upper side 38 and a shell side 40 connecting the upper side 38 and the lower side 39 are not coated.
  • the thickness of the coating 14 can be varied within wide ranges.
  • the thickness of the coating 14 is 10% or less of the thickness of the entire propellant element 10.
  • Such a propellant element 10 has an even better ignitability, since the ignition behavior of the pyrotechnic pre-ignition agent to the pyrotechnic material of the core 12 is further improved.
  • the edge portion 46 Through the edge portion 46, at least a portion of the core 12 is directly accessible via the surroundings of the propellant element 10. In this way, the ignition behavior of the propellant element 10 can be influenced more strongly by the pyrotechnic material of the core 12, in addition to the pyrotechnic pre-ignition agent.
  • the coating 14 of the pyrotechnic pre-ignition agent is again applied.
  • Fig. 9 shows a seventh embodiment of the fuel element 10, which is constructed similarly to the third embodiment of Fig. 5. However, in the seventh embodiment, only a part of the casing 42 is formed by the coating 14 of pyrotechnic pre-ignition agent, namely that part of the casing 42 which is applied to the upper side 38 of the first core region 15.
  • the remaining part of the casing 42 is formed from a second pyrotechnic material, i.e. from the second core region 16.
  • the core 12 is formed from the core region 15 and the second core region 16, which also forms the casing 42, which is perforated by the edge sections 46.
  • the upper punch 56 is designed to be displaced in the direction of the pressing die 58 and to engage into the receiving chamber 62.
  • the upper punch 56 has a cylindrical shape and comprises an inner punch 64 and an outer punch 66.
  • the outer punch 66 laterally encloses the inner punch 64, with the inner punch 64 being slidably mounted in the outer punch 66. Thus, the inner punch 64 can be displaced against the outer punch 66. Furthermore, the outer punch 66 forms a common end face 68 with the inner punch 64. with which the upper punch 56 engages into the receiving chamber 62 of the pressing die 58 during a compression process.
  • the receiving chamber 62 is filled with the pyrotechnic pre-ignition agent (S1).
  • the upper punch 56 is pressed into the receiving chamber 62 of the pressing die 58, and the pyrotechnic pre-ignition agent is compressed (S2).
  • the inner punch 64 is pushed further into the receiving chamber 62 than the outer punch 66.
  • the pyrotechnic pre-ignition agent 14 can be formed while maintaining a casing bottom 70. Since the outer punch 66 is pushed into the receiving chamber 62 offset from the inner punch 64, a casing bottom 70 with a U-shaped cross-section is formed. The casing bottom 70 is open toward the upper punch 56.
  • the upper punch 56 is then withdrawn from the pressing die 58 (S3) and the finished pressed casing bottom 70 remains in the pressing die 58.
  • the receiving chamber 62 is filled with the first pyrotechnic material (S4). It is understood that, depending on the desired embodiment, a second pyrotechnic material may also be used.
  • the upper punch 56 is pressed back into the receiving chamber 62, with initially only the outer punch 66 being pressed into the receiving chamber 62 (S5).
  • an edge portion 46 made of the first pyrotechnic material is pressed onto laterally projecting areas of the casing's underside 70.
  • the inner punch 64 is pushed into the receiving chamber 62 (S6) until it again forms a common end face with the outer punch 66.
  • the core 12 is pressed into the casing bottom 70, which is open toward the upper punch 56.
  • the upper punch 56 is then withdrawn from the pressing die 58 again (S7) to obtain a compact consisting of the casing bottom 70, which comprises a pre-compacted core 12 with edge section 46.
  • the compact is moved by the lower punch 60 in the receiving chamber 62 in the direction of the upper punch 56 (S8).
  • the upper punch 56 is pressed back into the receiving chamber 62 or the pressing die 58 is moved or, generally speaking, the distance between the upper punch 56 and the pressing die 58 is reduced to such an extent that the pyrotechnic pre-ignition agent is pressed in the form of a jacketed tablet, maintaining a casing top 72 and thus the finished propellant element 10 (S10).
  • the upper punch 56 is retracted from the receiving chamber 62. Furthermore, the lower punch 60 is moved toward the upper punch 56 until the receiving chamber 62 is completely occupied by the lower punch 60 (S11). The coated tablet can be removed from the press 54.
  • Analogous intermediate steps can be used to produce further layers or partial layers by means of pressing, for example by producing the casing underside 70 from the second pyrotechnic material.
  • Figure 16 describes the sequences of a method for producing a fuel element 10 according to the invention in a shell tablet with a biconvex, optionally an asymmetrically biconvex, shaped core 12 with edge portion 46.
  • convex and concave means that only the respective end faces of punches 74, 76, and 78 have a curvature.
  • the curvature of the convex upper punch 74 corresponds to that of the concave lower punch 78.
  • the production of an asymmetrically biconvex coated tablet is achieved by using a concave lower punch 78 and a concave upper punch 76, which do not have the same curvature on their end faces.
  • the front side of the convex upper punch 76 has a curvature with a radius that corresponds to the curvature of the front side of the concave lower punch 78.
  • the concave lower punch 78 is curved such that the convex upper punch 74 can engage with the lower punch 52, in particular such that the convex upper punch 74 can engage with the lower punch 52 in a form-fitting manner.
  • the front side of the upper punch 74 preferably has a convex shape that is complementary to a concave shape of the lower punch 78.
  • the receiving chamber 62 is filled with the pyrotechnic pre-ignition agent (S1).
  • the convex upper punch 74 is first pushed back from the receiving chamber 62 and removed from the press (S3).
  • the receiving chamber 62 is filled with the first pyrotechnic material (S4).
  • the first pyrotechnic material is compressed by pushing the concave upper punch 76 into the receiving chamber 62, thereby obtaining the core 12 with an edge portion 46 (S5).
  • a concave upper punch 76 can be used for the above step, which has a curvature different from the curvature of the concave lower punch 78.
  • an asymmetrically biconvex shaped core 12 can be pressed.
  • the concave upper punch 76 can be pushed out of the pressing die 58 again and the pyrotechnic pre-ignition agent can be filled into the receiving chamber 62 again (S6).
  • the pyrotechnic pre-ignition agent 14 can be fully pressed by the concave upper punch 76 or the lower punch 78 is moved or, generally speaking, the distance between the upper and lower punches is reduced in order to achieve compression, while maintaining a convexly shaped envelope upper side 72 (S7).

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Combustion & Propulsion (AREA)
  • Air Bags (AREA)

Abstract

L'invention concerne un élément combustible (10) sous la forme d'une tablette pour un générateur de gaz destiné à être utilisé dans un dispositif de sécurité. La tablette comprend un noyau (12) en matériau pyrotechnique et un revêtement (14) qui est appliqué sur le noyau (12) et qui est constitué d'un agent de pré-allumage pyrotechnique, le matériau pyrotechnique et l'agent de pré-allumage pyrotechnique étant différents l'un de l'autre, l'agent de pré-allumage pyrotechnique présentant un point de déflagration de 500 K ou moins. L'invention concerne en outre un procédé de production d'un tel élément combustible (10) et l'utilisation d'un tel élément combustible (10).
PCT/EP2024/073992 2023-09-05 2024-08-28 Élément combustible pour générateur de gaz, son procédé de production et son utilisation Pending WO2025051596A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102023123795.0A DE102023123795A1 (de) 2023-09-05 2023-09-05 Treibstoffelement für einen Gasgenerator, Verfahren zu dessen Herstellung und Verwendung des Treibstoffelements
DE102023123795.0 2023-09-05

Publications (1)

Publication Number Publication Date
WO2025051596A1 true WO2025051596A1 (fr) 2025-03-13

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WO (1) WO2025051596A1 (fr)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6143103A (en) * 1998-01-27 2000-11-07 Trw Inc. Gas generating material for vehicle occupant protection device
JP2001278690A (ja) 2000-03-30 2001-10-10 Fuji Heavy Ind Ltd エアバッグ用ガス発生体
EP1890986B1 (fr) * 2005-06-02 2013-01-16 RUAG Ammotec GmbH Agent pyrotechnique
DE102012024799A1 (de) 2012-12-19 2014-06-26 Trw Airbag Systems Gmbh Gepresstes Treibladungselement, Verfahren zu dessen Herstellung und Gasgenerator mit Treibladungselement
DE102019121477A1 (de) * 2019-08-08 2021-02-11 Zf Airbag Germany Gmbh Gasgenerator und verwendung eines flexiblen trägers als frühzündeinrichtung in einem gasgenerator
DE102022108291A1 (de) 2022-04-06 2023-10-12 Zf Airbag Germany Gmbh Gepresstes Treibstoffelement, Verfahren zu dessen Herstellung und Gasgenerator mit Treibstoffelement

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4806180A (en) * 1987-12-10 1989-02-21 Trw Vehicle Safety Systems Inc. Gas generating material
DE3933555C1 (en) * 1989-10-07 1991-02-21 Bayern-Chemie Gesellschaft Fuer Flugchemische Antriebe Mbh, 8261 Aschau, De Vehicle safety bag inflation change - is flat with slow-burning outer section ignited first and surrounding fast-burning central section
DE102006026339A1 (de) * 2005-06-02 2006-12-07 Ruag Ammotec Gmbh Pyrotechnisches Mittel
US20180127328A1 (en) * 2014-11-10 2018-05-10 Ruag Ammotec Gmbh Thermal pre-ignition agent

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6143103A (en) * 1998-01-27 2000-11-07 Trw Inc. Gas generating material for vehicle occupant protection device
JP2001278690A (ja) 2000-03-30 2001-10-10 Fuji Heavy Ind Ltd エアバッグ用ガス発生体
EP1890986B1 (fr) * 2005-06-02 2013-01-16 RUAG Ammotec GmbH Agent pyrotechnique
DE102012024799A1 (de) 2012-12-19 2014-06-26 Trw Airbag Systems Gmbh Gepresstes Treibladungselement, Verfahren zu dessen Herstellung und Gasgenerator mit Treibladungselement
DE102019121477A1 (de) * 2019-08-08 2021-02-11 Zf Airbag Germany Gmbh Gasgenerator und verwendung eines flexiblen trägers als frühzündeinrichtung in einem gasgenerator
DE102022108291A1 (de) 2022-04-06 2023-10-12 Zf Airbag Germany Gmbh Gepresstes Treibstoffelement, Verfahren zu dessen Herstellung und Gasgenerator mit Treibstoffelement

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