KR20000035844A - Use of mixed gases in hybrid air bag inflators - Google Patents

Abstract

PURPOSE: A use of mixed gases in hybrid air bag in flators is provided for a method of generating non-toxic gases without particulates and for an improvement in a hybrid in flator for producing said non-toxic gases and, especially for use in generating the gases for a vehicle occupant restraint. CONSTITUTION: 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. An 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

The present invention includes the use of oxygen or a mixture of air and argon to control the oxidation level of the overall propellant. The fuel rich solid propellant composition can be varied and the amount of oxygen to argon can be varied such that the exhaust product of the fuel rich composition produces non-toxic products exemplified by carbon dioxide, water vapor, and nitrogen.

Hybrid inflators generally used solid propellants to heat the gas to inflate the air bags. One of the problems with hybrid expanders was the amount of particulate from the KClO ₄ oxidant used in the propellant. Particulates can be removed by using propellant compounds such as 5-aminotetrazole (5-AT), aminoguanidine nitrate (AGN) or mixtures thereof. In addition, as an oxidizing agent, ammonium nitrate can replace KCLO ₄ .

The above concept is not disclosed in the prior art. In the section below line 48 of column 3 of US Pat. No. 4,909,549, the inventors disclose the use of a gas comprising a first gas mixture diluted with a second gas mixture (air), which provides several advantages. . The advantages listed include cooling the first gas mixture by dilution, thereby avoiding the possibility of burns by passengers of the plane or car in which the crash bag was used. Air dilution of the first gas mixture reduces the level of toxic species present to a much lower, acceptable level. Therefore, it is practical to employ tetrazole or triazole compounds containing hydrogen in the molecule, since the hydrogen concentration in the gas produced can generally be reduced to very low levels by oxidation. Nevertheless, this patent document does not disclose or suggest control of the argon to oxygen ratio taught by the present invention.

In the fifth column of US Pat. No. 5,199,740, hot potassium chloride, as well as other components in the heating gas generated by combustion of the propellant, is described as entering the pressure vessel and impinging on the inner wall of the vessel portion. As the heated combustion product enters the pressure vessel, the temperature of the pressurized argon gas will increase somewhat uniformly. As the temperature of the argon gas rises, the pressure is increased to a level that causes the rupture of the outflow rupture disk disposed in the stepped aperture, thereby allowing the gas to flow through the outlet opening in the manifold. Obviously, this is different from the concept of the present invention, and in the present invention, by varying the amount of oxygen to argon, the emission products of the fuel rich composition can be controlled to produce non-toxic products. And higher temperature gas mixtures than those produced with air, due to the low heat capacity of argon and some of the unidentified characteristics of this gas. Thus, less argon and oxygen are needed at a given gas mixture temperature, allowing reduced system size to be employed without compromising the efficiency of the system.

48 or less of specification column 1 of US Pat. No. 5,348,344, inert gas, preferably nitrogen or argon (column 3), together with fuel gas which is preferably hydrogen and / or methane but may be other combustible gas, or It is disclosed to provide mixtures thereof. The oxidant gas is preferably oxygen. In one embodiment of the invention, the storage means is a single container holding the inert gas, fuel gas, and oxidant gas as a gas mixture. In another embodiment, the first container holds a fuel gas, the second container contains an excess of oxidant, the storage means defines a combustion chamber such that the fuel gas and the oxidant gas are contained within the combustion chamber, and the combustion chamber The mixture of gases is ignited within.

By the above method, the expansion rate of the inflatable device and the pressure therein can be controlled by selecting the amounts of fuel gas and oxidant gas to yield the desired combustion rate, and the combustion rate as described above is again determined by the predetermined amount into the inflatable device. Fix the volumetric flow rate of the warm gas. In addition, the expansion rate can be controlled by a flow control orifice or the like through which gas flows into the inflatable device. The above patent document does not specify an understanding of the importance of the presence of argon and therefore describes substantially different methods and apparatus than those related to the present invention.

Described below by column 2, line 35 of US Reissue Patent No. 29,228 is an embodiment in which the confinement device expands under the influence of a high velocity fluid source, the fluid being a gas generator of the type of solid propellant rocket motor. The gas generator provides a high speed, high temperature gas stream which cooperates with the nozzle to draw large amounts of air into the confinement device. The hot gas is cooled by a large amount of air so that the container is not heated to excessive temperatures. The patent document does not disclose the use of argon, but the concepts taught in the specification do not lead those skilled in the art to the invention claimed herein.

The characteristics of lead-free airbag propellants are listed below:

Characteristics of lead free airbag propellant

Lead-free propellants generate only gaseous combustion products such as CO ₂ , H ₂ O, N ₂ , and inert gases (eg argon). Therefore, they are limited to the chemical elements C, H, O, N, and inert gas (helium, argon) and the like.

Alkali metal fuels (e.g. NaN ₃ ), oxidants (e.g. KClO ₄ ), and alkaline earth oxidants (e.g. Sr (NO ₃ ) ₂ ) generate particulates (e.g. Na ₂ O, KCl and SrO) . Therefore they cannot be used in lead-free propellants.

Gun propellents based on nitrocellulose are good lead-free propellants but cannot be used in air bags due to storage temperature requirements.

Lead-free propellants, including RDX and nitramines, such as HMX, can withstand high temperature storage and thus meet such requirements as airbag propellants or candidates for use with optional oxygen / argon compositions.

Lead-free propellants containing ammonium nitrate can withstand high temperature storage but not temperature cycling through 50 ° C. This is excluded because the lower storage temperature is -40 ° C.

However, lead-free propellants, including ammonium nitrate eutectic mixtures, are known to withstand temperature cycling.

These propellants must be carefully formulated to prevent the formation of toxic combustion products (ie HCN and NO _X ).

The following table is provided to illustrate the desirable properties required for lead-free hybrid air bag propellants.

Characteristics of lead-free hybrid airbag propellant

Characteristics Requirements Desired Conditions

Particulates <1.0 g zero

Production method casting, extrusion, injection molding extrusion, injection molding

Or press or casting

Stability 95 ℃ 107 ℃

Sensitivity Sensitivity

Combustion complete combustion complete combustion

Toxicity Nontoxic Nontoxic

No emissions No odor

Gas hybrid (argon, air argon

Or O ₂ -argon)

The present invention relates to a method for generating a non-toxic gas as a whole without particulates and to an improvement of a hybrid inflator for generating said non-toxic gas and in particular for generating a gas for a passenger restraint device of a vehicle.

The type of inflator for inflating air bags employed in inflatable restraint systems is well known in the art. One of the inflator types uses a large amount of storage compression gas that is selectively released to inflate the air bag. Some types in this regard generate a gas source from combustible gas generating materials that provide a sufficient amount of gas to inflate the air bag upon ignition. In another type, the air bag inflation gas is provided by a combination of the storage compression gas and the combustion product of the gas generating material. The latter type is known as a hybrid expander.

In the past, hybrid inflators had some drawbacks. Combustion of propellants and initiators in such inflators resulted in the production of undesirable particulate matter. Employing the emitters of the inflator containing particulates to inflate the airbags resulted in the particulates being passed into the vehicle and inhaled by the passengers of the vehicle.

In addition to the inhalation of gas particles by the passengers in the vehicle, when these particles are dispersed or scattered in the air, they will take the form of smoke, causing excessive concern that there will be a fire.

As is known in the art, air or other gas and solid gas generating materials are stored in containers. When there is a sudden vehicle deceleration that suggests a collision, the container gas is released to inflate the vehicle's passenger restraint, i.e., the air bag, which protects the passenger of the vehicle from serious injury. In the event of a sudden vehicle deceleration such as occurs in the collision of the vehicle, the gas generating substance is ignited. When the gas generating material is burned, it heats the storage gas and forms a hot expanding gas or vapor which is mixed with it, and the heated gas mixture is flooded with an air bag.

The present invention relates to improvements in inflator technology and provides a clean odorless gas that inflates devices such as air bags without particulates or toxic papers. For completeness, a conventional inflator mechanism will be described with reference to the drawings. The inflator structure is apparent from the accompanying drawings.

Referring to FIG. 1, which illustrates a conventional passenger-side inflator, the igniter 1 is ignited in response to a sensor (not shown) that senses a rapid deceleration indicative of a crash. The igniter emits a hot gas that ignites the auxiliary charge 2, which burns the main generant charge 8 to generate an expanded gas mixture 3. When the pressure increases to a certain point, the seal disc 6 bursts, allowing the gas mixture to be discharged through the outlet port 5 to the manifold 4 to inflate the air bag. The generant container 9 houses the main charge filling section 8. All live parts and expansion gas mixture are enclosed in a pressure tank 7.

The following examples illustrate the efficacy of the disclosed invention. Examples 1-3 disclose certain aspects of the method of the present invention. Although Example 4 lacks some data provided in other examples, this example is included in the present disclosure to provide a comparison of the presence of toxic products obtained when argon is a hybrid gas in the reactor instead of air. Make it possible.

Example 1

Composition: AGN / Polycarbonate Binder

0-0.2 g of fine particles

Production method press

Stability 0 K-107 ℃

No sensitivity

Combustion complete combustion

Toxicity Nontoxic

Hybrid gas argon / O ₂ or air

Ignition part lead free

Example 2

Composition: 84.8 wt% HMX with 15.2% HTPB (Arcadene brand) as binder

0-0.2 g of fine particles

Production method casting or injection molding

Stability 0 K-107 ℃

Sensitivity Insensitive to ESD and Friction

Combustion rate

Combustion complete combustion

Toxicity Nontoxic

Hybrid gas O ₂ / argon

Ignition part flexible

Example 3

Composition: HTPB / Nitramine

0.2 g of fine particles

Production casting or injection molding

Stability 0 K-107 ℃

No sensitivity

0.15 ips at 1000 psi

Combustion complete combustion

Toxicity Nontoxic

Hybrid gas O ₂ / argon

Ignition part B / KNO ₃

In the compositions of Examples 2 and 3, compounds such as isophorone diisocyanate (IPDI) may be included as curing agents for butadiene binders in which the terminal groups are hydroxyl groups.

Example 4

Composition: HMX or RDX (Nitramine) / HTPB

Toxic emissions products contain NO _x , NO ₂ and NH ₃ in amounts that are toxic.

Hybrid gas air

The process of the present invention which generates a non-toxic gas without particulates comprises the steps of igniting the propellant in the presence of an ammonium nitrate oxidant and a suitable propellant, for example RDX (RDX is 1,3,5 trinitro-1,3,5 tree). Azacyclohexane or cyclotrimethylenenitramine.) And / or HMX (HMX is 1,3,5,7-tetranitro-1,3,5,7- tetraazacyclooctane or cyclotetramethylenetetranitramine. Using aminoguanidine or nitramine. In the presence of argon and molecular oxygen containing gas in which the ratio of molecular oxygen-containing gas to argon is controlled to minimize toxicity, the non-toxic reaction products in the exhaust gas include carbon dioxide, H ₂ O, N _2, and mixtures thereof. By using a selected mixture of argon and molecular oxygen containing gas, the oxidation level of the total propellant can be controlled to fall within the desired range.

Another feature of the invention involves the use of a binder in conjunction with the aforementioned propellant. Polyvinyl alcohol (PVA) binders are likewise very effective, although polycarbonate binders may be used with amino acid guanidine (AGN) propellants in the form of compression filled pellets. The binder will comprise about 5% by weight of the propellant weight.

Ignition of the propellant occurs in the presence of argon to oxygen in a controlled ratio. For example, 21 volumes of oxygen are used with 79 volumes of argon. However, depending on all other conditions, 15 to 30 volume parts of oxygen can be used with the remaining volume of argon.

The use of a mixture of argon, oxygen, and a lead-free propellant, such as 95% aminoguanidine nitrate and 5% polycarbonate binder in the form of compression-filled pellets, has the advantage that the packing is non-hygroscopic. However, particularly preferred compositions comprise about 5% by weight polyvinyl alcohol and about 95% by weight aminoguanidine nitrate used with 20% oxygen and 80% argon.

The method of the present invention is suitable for inflating airbags for automobiles that are used as passenger restraint devices at rapid decelerations, such as in a vehicle crash.

By using means to convert the ratio of molecular oxygen containing gas to argon, the particulates and toxic amounts of nitrogen oxides, ammonia, and nitric acid in the exhaust gas are minimized or at least within an acceptable range. In addition, smaller size inflator devices may be used. This is due to the gas mixture temperature higher than that attainable by the low heat capacity of argon, which allows for the use of reduced amounts of argon and oxygen, thus allowing the use of smaller equipment.

The invention has been described in detail with reference to the specific embodiments disclosed. However, the scope of the present invention is broader and appropriately defined by the appended claims.

Claims (28)

Performing ignition of the propellant composition with an effective oxidant, using a suitable propellant comprising aminoguanidine nitrate with a suitable binder in the presence of argon and molecular oxygen containing gas, and providing a nontoxic reaction product to the exhaust gas. And optionally providing a ratio of said molecular oxygen containing gas to argon prior to ignition. The method of claim 1 wherein the non-toxic reaction product in the exhaust gas is selected from the group consisting of CO ₂ , H ₂ O, N ₂ , and mixtures thereof. The method of claim 1, wherein the selected mixture of argon and molecular oxygen containing gas can be adjusted to within the desired range by controlling the oxidation level of the propellant composition. The method of claim 1, wherein the binder is selected from the group consisting of HTPB, polyvinyl alcohol, and polycarbonate. The method of claim 1, wherein the binder is polycarbonate and the propellant composition is in the form of compression filled pellets. 6. The method of claim 5, wherein the binder comprises about 5% by weight based on the weight of the propellant. 7. The method of claim 6, wherein the ignition environment comprises about 21 volume parts of oxygen and about 79 volume parts of argon. 7. The method of claim 6, wherein the ignition environment comprises from about 15 to about 30 volume parts of oxygen and the remaining volume of argon. The method of claim 1 wherein the binder is HTPB and the propellant composition is in the form of a cast, injection molded or extruded mass. 10. The method of claim 9, wherein the propellant composition further comprises a curing agent. 5. The method of claim 4, wherein the propellant composition comprises about 95% by weight aminoguanidine nitrate and the packing part is non-hygroscopic. The method of claim 1, wherein the generated gas is used to inflate an automotive air bag. 12. The method of claim 11, wherein the generated gas is used to inflate an automotive air bag. In an automobile airbag filling gas generation method using a combination of air and argon as an environment in which a compound constituting the gas main supply source is combusted to generate an airbag inflation gas, Using a propellant composition comprising aminoguanidine nitrate as said primary source with a suitable binder; And during ignition, using a ratio of air to argon in which the particulates, toxic nitrogen oxides, ammonia, HCN, and nitric acid are minimized in the exhaust gas. . 15. The method of claim 14, wherein the non-toxic product in the exhaust gas is selected from the group consisting of CO ₂ , H ₂ O, N ₂ , and mixtures thereof. 15. The method of claim 14, wherein the propellant composition is used with a polybutadiene binder whose terminal group is a hydroxyl group. 15. The method of claim 14, wherein the binder is polycarbonate. 15. The method of claim 14, wherein said propellant composition comprises a polycarbonate binder. 19. The method of claim 18, wherein the propellant composition comprises 5 weight percent polycarbonate binder. 20. The method of claim 19, wherein the propellant composition comprises aminoguanidine nitrate, and the propellant composition and the binder are in the form of pressurized pellet fillings. 18. The method of claim 16, wherein the curing agent is included with the binder. The method of claim 1, wherein the binder is polyvinyl alcohol. The propellant composition of claim 1, wherein said propellant composition comprises about 95 weight percent aminoguanidine nitrate and about 5 weight percent polyvinyl alcohol as a binder, said composition being ignited in the presence of 20% oxygen and 80% argon. A method for generating an air bag charging gas for a vehicle, characterized in that 15. The method of claim 14, wherein the compound constituting the gas main source is AGN, and polyvinyl alcohol is used as the binder. 25. The method of claim 24, wherein the polyvinyl alcohol is present in an amount of 5% by weight. 21. The method of claim 20, wherein the binder is polyvinyl alcohol. 27. The method of claim 26, wherein the polyvinyl alcohol binder is present in an amount of 5% by weight based on the weight of the propellant composition. 22. The method of claim 21, wherein said hardener is IPDI.