MXPA99001980A

MXPA99001980A - Use of mixed gases in hybrid air bag inflators

Info

Publication number: MXPA99001980A
Application number: MXPA/A/1999/001980A
Authority: MX
Inventors: S Scheffee Robert; R Sides James; D Martin James
Original assignee: Atlantic Research Corporation
Filing date: 1999-03-01
Publication date: 2000-02-02

Abstract

Particulate-free non-toxic gases are generated in a hybrid generator device by conducting the ignition of the propellant with an effective oxidizer, using a mixture of a molecular oxygen-containing gas and argon by varying the ratio of the gas to argon to provide only non-toxic reaction products in the exhaust gas. The inventive device includes an initiator (1), which ignites in response to a sensor and gives off hot gas that ignites the ignition charge (2) which causes the main generant charge (8) to combust, generating the inflation gas mixture (3). When the pressure in the gas mixture increases to a certain point, the seal disc (6) ruptures permitting the gas mixture to exit the manifold (4) through the outlet ports (5) and inflate an air bag. The generant container (9) holds the main generant charge (8). All the charges and the inflation gas mixture are enclosed in the pressure tank (7).

Description

USE OF MIXED GASES IN HYBRID AIR BAG INFLATORS Field of the Invention The present invention relates generally to a method for generating non-toxic gases without particles and to an improvement in a hybrid inflator to produce such non-toxic gases and, especially to be used in the generation of gases to restrict a occupant of the vehicle. The technique is replete with types of inflators for inflating an air bag used in an inflatable restraint system. Among the types of inflators is one that uses a quantity of stored compressed gas, which is selectively released to inflate the airbag. A related type generates a gas source of a combustible gas generating material which, after ignition, provides the amount of gas sufficient to inflate the air bag. In yet another type, the inflation gas of the airbag is provided by the combination of a stored compressed gas and the combustion products of the gas generating material. This last type is known as a hybrid inflator. In the past, hybrid inflators have been subject to certain disadvantages. The ignition of the propellant and the starting materials in such inflators, resulted in the production of undesirable particulate matter. The use of inflator emissions that contain particles to inflate an air bag may result in the particles passing into the vehicle and being inhaled by the occupants thereof. In addition to the particulate material transported by the gas that is being inhaled by the passengers in the vehicle, such particles, if dispersed and transported by air, can give the appearance of smoke and cause undue concern that fire may be present. As is well known in this field, air or other gas and solid gas generating material are stored in a container. If there is a high deceleration rate of the vehicle, indicative of a collision, the gas in the container is released to inflate the vehicle occupant restraint device, i.e., an air bag, which restricts and protects the vehicle occupant. of serious damages. After a deceleration rate of the vehicle occurs, such as occurs in the collision of a vehicle, the gas generating material burns. When such gas generating material is burned, it forms hot expanded gases or vapors, which are heated and mixed with the stored gases, and the hot gas mixture is accelerated towards the air bag.

Description of the Prior Art The present invention involves the use of mixtures of oxygen or air with argon, or the like, to allow control of the oxidation level of the total propellant. The fuel-rich solid propellant formulations can vary and the amounts of oxygen to argon can also vary, so that the exhaust products of the fuel-rich formulation give non-toxic products, and are used by carbon dioxide, water and nitrogen . Hybrid inflators have generally used a solid propellant to heat the argon gas to inflate an airbag One of the problems with hybrids has been the amount of KC104 oxidant particles used in the propellant. Through the use of propellant compounds, such as 5-aminotetrazole (5-AT), aminoguanidine nitrate (AGN) or mixtures thereof, the oxidant ammonium nitrate can be substituted by KC104. taught in the prior art U.S. Patent No. 4,909,549, in column 3, beginning on line 48, the inventors describe the use of gases comprising a mixture of dilute primary gas with a secondary gas mixture (air), which provides several advantages.The benefits listed include cooling the primary gas mixture by dilution, thus avoiding the ignition potential of the occupants of an aircraft or automobile, in which the crash bag is used. Diluting the air from the primary gas mixture reduces the level of toxic species present to much lower, acceptable levels- Thus, the use of tetrazol or triazole compounds containing hydrogen in the molecule is practical, since the concentration of hydrogen in the produced gas can generally be reduced by oxidation to very low levels. However, the reference does not disclose or suggest controlling the argon to oxygen ratio as taught by the inventors herein. In US Patent No. 5,199,740, in column 5, potassium chloride, as well as other constituents in the hot gases produced by the ignition of the propellant, are described, such as those entering the pressure vessel and colliding on the inner wall of the part the container. When the hot combustion products enter the pressure vessel, the temperature of the pressurized argon gas will increase very uniformly. When the temperature of the argon gas rises, its pressure will increase to a level, which will cause the rupture of the external rupture disc placed in a through hole, thus allowing the gases to flow through the outlet openings in the multiple. Clearly, the above is strange in the concept of the present invention, wherein the addition of various amounts of oxygen to argon allows the exhaust products and the fuel rich formulations to be controlled to give non-toxic products. Such addition also allows to reach higher temperatures of the gas mixture than those produced with a propellant and air, due to the low heat capacity of the argon and some unique unidentified properties of this gas. Therefore, at a given gas mixture temperature, less argon and oxygen are necessary, resulting in the ability to employ a reduced size system without compromising the effectiveness of the system. In U.S. Patent No. 5,348,344, the specification, in column 1, beginning at line 48, describes the provision of an inert gas, preferably nitrogen or argon (column 3) or a mixture thereof, with a gas fuel, which is preferably hydrogen and / or methane, but which can be any other flammable gas. The oxidizing gas is preferably oxygen. In one embodiment of the invention, the containment means is a single container for containing the inert gas, the fuel gas and the oxidizing gas as a mixture of gases. In another modality, a / first container contains the combustible gas, a second confines an excess of oxidizing gas and the containment means define a combustion chamber, in which the fuel gas and oxidizing gas are received and in which the gas mixture is burned. By the above method, the inflation rate of and the pressure in an inflatable device can be controlled by selecting the amount of fuel gas and oxidizing gas to give a desired ignition rate, which in turn, sets the predetermined volumetric flow velocity of hot gas towards the inflatable device. Additionally, the rate of inflation can be controlled by flow control orifices or the like, through which the gas flows into the inflatable device. It is evident that the reference does not evidence an appreciation of the critical aspects of the presence of argon and, thus, describes a device and method materially different from those related to the present invention. In US Reissue Patent 29,228, in column 2, beginning on line 35, the inventor describes a mode, wherein the confinement is inflated under the influence of a high velocity fluid source, the fluid is a gas generator of the type of rocket motor with solid propellant. The gas generator provides a high velocity flow of hot gas, which cooperates with a nozzle to extract the large volume of air in the confinement. The hot gas is cooled by the large volume of air, so that the container is not heated to excessive temperatures. Not only does the reference not describe the use of argon, but the concept taught in the specification may not have led an expert in the art to the invention now claimed. The attributes of smokeless air bag propellants are listed below: ATTRIBUTES OF THE PROFESSIONALS OF SMOKE-FREE AIR BAGS • The smokeless propellants generate only gaseous combustion products such as C02, H20, N2, and noble gases (for example, Ar). In this way, they are limited to the chemical elements C, H, 0, N, and noble gases (He, Ar) • Alkali metal fuels (for example, NaN3) and oxidants (for example, KC104) and alkaline earth oxidizers [for example, Sr (N03) z] generate particles. { for example, Na20, KCl, and SrO). In this way, they can not be used in smokeless propellants. • Nitrocellulose cannon propellants are excellent smokeless propellants, but can not be used in air pockets due to the storage temperature requirement. • Smokeless propellant containing nitrates, such as RDX and HMX, can withstand high storage * temperature and, thus, satisfy this requirement to be candidates for or an air bag propellant for use with selective oxygen / argon formulations. • Smokeless propellants containing ammonium nitrate can withstand high temperature storage, but not temperature cycles of up to 50 ° C. They are impeded because the lowest storage temperature is 40 ° C. However, it has been found that propellants containing eutectic ammonium nitrate resist the temperature cycle. • These propellants must be carefully formulated to prevent the formation of toxic combustion products (that is, HCN and NO To describe the required and desired characteristics of hybrid smokeless air bag propellants, the following tabulation is provided: CHARACTERISTICS OF THE PROPELLERS OF HYBRID AIRBAG WITHOUT SMOKE CHARACTERISTICS I REQUIRED DESIRED i Particles < 1.0 grams Zero Production Emptying, extrusion, extrusion, molding injection molding, or injection, or emptying pressure Stability 95 ° C 107 ° C Sensitivity Insensitive Insensitive Combustion Complete combustion Complete Toxicity Non-toxic Non-toxic Exhaust None Odorless Hybrid gas (argon, Argon air, or 02-argon Detailed Description of the Invention and Preferred Modality The invention of interest relates to an improvement in the technology of the inflator and provides an odorless, clean gas, free of particles or toxic species to inflate devices such as airbags and the like. With a more complete interest, a conventional inflator mechanism is described in the figure of the drawing. The structure of the inflator is evident from the labeled diagram. In the figure describing a conventional passenger side inflator, the inflator 1 burns in response to a sensor (not shown) that detects a rapid deceleration, indicative of a collision. The initiator gives hot discharge gases that burn the ignition charge 2, which causes the main generating charge 8 to burn, generating the inflation gas mixture 3. When the pressure in the gas mixture increases to a certain point , the sealing disc 6 is broken allowing the gas mixture to exit the manifold 4 through the outlet gates 5 and inflate the air bag. The generator vessel 9 maintains the main generating charge 8. All the loads and inflation gas mixture are enclosed in the pressure tank 7. The following examples demonstrate the effectiveness of the invention described. Examples 1-3 describe certain aspects of the inventor's method. Although from Example 4 it lacks some data provided in the other examples, the example was included in this description, to allow a comparison to be made between the presence of the toxic products obtained when the argon, instead of the air, is the hybrid gas in the reactor.

Example 1 Composition: AGN / polycarbonate binder Particles 0 - 2 g Pressurized production Stability Good - 107 ° C Sensitivity Insensitive Complete Combustion Toxicity Non-toxic Hybrid gas Argon / 02 or air Ignitor Smokeless Example 2 Composition: 84.8% by weight of HMX with 15.2% of HTPB (Arcadene®) as binder Particles 0 - 0.2 g Production Cast or injection molded Stability Good - 107 ° C Sensitivity Insensitive to ESD and friction Ignition speed Complete combustion Toxicity Non-toxic Hybrid Gas 02 / Argon Ignitor Smoke Example 3 Composition: HTPB / Nitramine Particles 0.2 g Production Casting or injection molding Stability Good at 107 ° C Sensitivity Insensitive Ignition speed 0.15 psi at 1000 psi (1,034 KPa at 6895 KPa) Complete Combustion Toxicity Non-toxic Hybrid Gas 02 / Argon Ignitor B / KN03 In the compositions of Examples 2 and 3, a compound, such as isophorone diisocyanate (IPDI), may be included as the curing agent for the hydroxy-terminated butadiene binder.

Example 4 Composition: HMX or RDX (nitramine) / HTPB Toxicity Exhaust products include toxic amounts of N0X, N02 and NH3 Gas Hybrid Air The method of the present invention for generating non-toxic gases without particles comprises conducting the ignition of the propellant in the presence of an ammonium nitrate oxidant and using a suitable propellant, for example, aminoguanidine nitrate or a nitramine, such as RDX and / or HMX1. In the presence of argon and a gas containing molecular oxygen, but without a controlled ratio of the gas containing molecular oxygen to argon, reduces the toxic values, the non-toxic reaction products in the exhaust gas include carbon dioxide, H20 , N2 and mixtures thereof. Using the selected mixtures of gas containing molecular oxygen with argon, it is possible to control the oxidation level of the total propellant so that it falls within a desired range. 1 RDX is 1, 3,5-trinitro-l, 3, 5-tria2: acyclohexane or cyclotrimethylenitrap na; and HMX is 1, 3, 5, 7-tetranitro-l, 3, 5, 7-tetraazocyclooctane or cyclotetramethylene tranex. Another aspect of the present invention involves the use of a binder with the described propellant. Although a polycarbonate binder may be used with the aminoguanidine nitrate propellant (AGN) in the form of a granular propellant charge, compressed, a polyvinyl alcohol binder (PVA) is also very effective. The binder will comprise about 5% by weight of the propellant. The ignition of the propellant takes place in the presence of controlled relations of argon to oxygen. For example, 21 parts by volume of oxygen are used with 79 parts by volume of argon. However, depending on all other conditions, from 15 to 30 parts by volume of oxygen with complementary volumes of argon can be used. Employing a mixture of oxygen with argon and a smokeless propellant, such as 95% aminoguanidine nitrate and 5% polycarbonate binder in a compressed granular filler, the advantage of having a non-hygroscopic filler is obtained. However, a particularly preferred formulation involves about 95% by weight, of aminoguanidine nitrate with about 5% by weight of polyvinyl alcohol used with 20% oxygen and 80% argon. The method of the present invention is well suited for inflating air bags of automotive vehicles, used as occupant restraint devices when a vehicle decelerates rapidly, such as in a collision. By using means to vary the ratios of the gas containing molecular oxygen to argon, the ammonia and nitric acid are reduced in the exhaust or at least they are placed in an acceptable range. Additionally, an inflator device of smaller size than what would be required in other circumstances may be used. This is due to the higher temperature of the gaseous mixture that can be reached due to the lower heat capacity of the argon, allowing the use of small amounts of argon and oxygen, and thus, smaller equipment. The invention has been described specifically with reference to the particular embodiments described. However, it should be understood that the scope of the invention is broader and is appropriately defined by the following claims.

Claims

CHAPTER CLAIMANT Having described the invention, it is considered as a novelty and, therefore, the content is claimed in the following:

1. A method for generating non-toxic gases without particles, characterized in that it comprises conducting an ignition of a propellant composition with an effective oxidant, using a suitable propellant comprising aminoguanidine nitrate, together with a suitable binder, in the presence of argon and a gas that contains molecular oxygen, and selectively provides a ratio of the gas containing molecular oxygen to argon before ignition to provide non-toxic reaction products in the exhaust gas.

The method according to claim 1, characterized in that the non-toxic reaction products in the exhaust gas are selected from the group consisting of C02, H20, N2 and mixtures thereof.

3. The method according to claim 1, characterized in that the selected mixture of the gas containing molecular oxygen with argon allows the oxidation level of the propellant composition to be controlled and falls within a desired range. .

The method according to claim 1, characterized in that the binder is selected from the group consisting of HTPB, polyvinyl alcohol and a polycarbonate.

5. The method according to claim 1, characterized in that the binder is polycarbonate, and the propellant composition is in the form of a compressed granular filler.

6. The method according to claim 5, characterized in that the binder comprises about 5% by weight of the propellant.

The method of sonification with claim 6, characterized in that the ignition environment comprises approximately 21 parts by volume of oxygen and approximately 79 parts by volume of argon.

The method according to claim 6, characterized in that the ignition environment comprises approximately 15 to approximately 30 parts by volume of oxygen with a complementary volume of argon.

9. The method of compliance with the claim 1, characterized in that the binder is HTPB and the propellant composition is in the form of an emptied mass, injection molded or extruded.

10. The method according to claim 9, characterized in that the propellant composition also includes a curing agent.

The method according to claim 4, characterized in that the propellant composition comprises approximately 95% by weight of aminoguanidine nitrate and the charge is not hygroscopic.

The method according to claim 1, characterized in that the gases generated are used to inflate a motor vehicle bag.

14. In a method for generating gas to fill an automotive vehicle airbag that uses a combination of air and argon as in the environment, in which the compounds that constitute the main source of gas are burned to generate the gas to inflate the air bag, the improvement characterized in that it comprises using a propellant composition comprising aminoguanidine nitrate, together with a suitable binder, as the main source; and employs during ignition, air to argon ratios with which the particles and toxic amounts of nitrogen oxide, ammonia, HCl and nitric acid in the exhaust gas are reduced.

15. The improvement according to claim 14, characterized in that the non-toxic products in the exhaust gas are selected from the group consisting of CQ2, H20, N2 and mixtures thereof.

16. The improvement according to claim 14, characterized in that the propellant composition is used as a hydroxy-terminated polybutadiene binder.

17. The improvement according to claim 14, characterized in that the binder is a polycarbonate.

18. The improvement according to claim 14, characterized in that the propellant composition includes a polycarbonate binder.

19. The improvement in accordance with the claim 18, characterized in that the propellant composition includes 5% by weight of polycarbonate binder.

20. The improvement in accordance with the claim 19, characterized in that the propellant composition includes aminoguanidine nitrate and the propellant composition and the binder are in the form of a compressed granular charge.

21. The improvement according to claim 16, characterized in that a curing agent is included with the binder.

22. The method according to claim 1, characterized in that the binder is polyvinyl alcohol.

23. The method according to claim 1, characterized in that the propellant composition comprises about 95% by weight of aminoguanidine nitrate and about 5% by weight of polyvinyl alcohol as the binder, the composition is formed in the presence of 20% oxygen and 80% of argon.

24. The improvement according to claim 14, characterized in that the compound constituting the main source of gas is AGN and a polyvinyl alcohol is used as a binder.

25. The improvement according to claim 24, characterized in that the polyvinyl alcohol is present in an amount of 5% by weight.

26. The improvement according to claim 20, characterized in that the binder is polyvinyl alcohol.

27. The improvement according to claim 26, characterized in that the polyvinyl alcohol binder is present in the amount of 5% by weight of the propellant composition.

28. The improvement according to claim 21, characterized in that the curing agent is IPDI.