U.S. patent application number 10/807289 was filed with the patent office on 2004-11-25 for gas-generating substances.
Invention is credited to Bley, Ulrich, Brede, Uwe, Hagel, Rainer, Redecker, Klaus.
Application Number | 20040231770 10/807289 |
Document ID | / |
Family ID | 33454070 |
Filed Date | 2004-11-25 |
United States Patent
Application |
20040231770 |
Kind Code |
A1 |
Bley, Ulrich ; et
al. |
November 25, 2004 |
Gas-generating substances
Abstract
The invention relates to a gas-generating substance which
consists of nitrous oxide and/or nitrogen monoxide and one or more
combustibles which are solid at room temperature and normal
pressure.
Inventors: |
Bley, Ulrich; (Nurnberg,
DE) ; Brede, Uwe; (Furth, DE) ; Hagel,
Rainer; (Erlangen, DE) ; Redecker, Klaus;
(Numberg, DE) |
Correspondence
Address: |
ANTONELLI, TERRY, STOUT & KRAUS, LLP
1300 NORTH SEVENTEENTH STREET
SUITE 1800
ARLINGTON
VA
22209-9889
US
|
Family ID: |
33454070 |
Appl. No.: |
10/807289 |
Filed: |
March 24, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10807289 |
Mar 24, 2004 |
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09913533 |
Dec 10, 2001 |
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09913533 |
Dec 10, 2001 |
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PCT/EP00/00274 |
Feb 15, 2000 |
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Current U.S.
Class: |
149/46 ;
149/61 |
Current CPC
Class: |
C06B 23/008 20130101;
C06D 5/10 20130101 |
Class at
Publication: |
149/046 ;
149/061 |
International
Class: |
C06B 031/02; C06B
031/28 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 19, 1999 |
DE |
199 07 241.8 |
Claims
What is claimed:
1. Gas-generating substance for a motor vehicle safety device,
comprising a mixture of N.sub.2O, NO and one or more fuels which
are solid at room temperature and standard pressure.
2. Gas-generating substance according to claim 1, characterised in
that it additionally contains, in order to control the reactivity
of the gases, at least one inert gas selected from the group
consisting of carbon dioxide, air, helium, neon and/or argon.
3. Gas-generating substance according to claim 1, characterised in
that it contains additions of smell-intensive gases in small
amounts for detecting leaks.
4. Gas-generating substance according to claim 1, characterised in
that it contains additions for improving the smell properties of
the combustion gases in the when utilization takes place.
5. Gas-generating substance according to claim 4, characterised in
that the additions for improving the smell properties of the
combustion gases comprise vanillin.
6. Gas-generating substance according to claim 1, characterised in
that the one or more fuels comprise polymers of a material selected
from the group consisting of ethylene, propylene, isoprene, and
styrene.
7. Gas-generating substance according to claim 1, characterised in
that the one or more fuels comprise oxygen-containing fuels derived
from a material selected from the group consisting of polyvinyl
acetates, polymethacrylates, polyterephthalates, polyesters,
polyethers, polycarbonates, polyoxymethylenes, oligosaccharides,
polysaccharides, cellulose, starch, polyvinyl acetals and polyvinyl
alcohols.
8. Gas-generating substance according to claim 1, further
comprising explosive substances as additional reactive components
of the fuels.
9. Gas-generating substance according to claim 1, further
comprising one or more compounds selected from the group consisting
of nitroguanidine (NiGu) 5-aminotetrazole, 5-aminotetrazole
nitrate, bistetrazole amine, bistetrazole, aminoguanidine nitrate,
diaminoguanidine nitrate, triaminoguanidine nitrate, guanidine
nitrate, dicyanodiamidine nitrate, diaminoguanidine azotetrazolate,
nitrotriazolone, dicanediamicune nitrate, hexogen, and octogen.
10. Gas-generating substance according to claim 1, further
comprising an additional fuel selected from the group consisting of
urea, fumaric acid, ascorbic acid, oxalic acid, cork, wood,
aluminium, titaniumboron, silicon, nitrides, azides and
B.sub.3N.sub.3.
11. Gas-generating substance according to claim 1, characterised in
that the one or more fuels are in the form of powder, granules,
pressings, cut fibres, twisted fibres, mats, woven fabrics, or
porous foams.
12. Gas-generating substance according to claim 1, characterised in
that the one or more fuels are surface-treated by being impregnated
or mixed with liquids or pasty substances, to control the
burn-off.
13. Gas-generating substance according to claim 1, further
comprising a catalyst selected from the group consisting of
ferrocene and derivatives, iron acetylacetonate and copper
acetylacetonate.
14. Gas-generating substance according to claim 1, further
comprising one or more oxidising agents selected from the group
consisting of nitrates of alkali and alkaline earth elements,
perchlorates of alkali and alkaline earth elements, ammonium
nitrate, ammonium perchlorate, zinc peroxide, perborates,
peroxodisulphates, permanganates, tin dioxide, manganese dioxide,
oxidising agents derived from nitramines and mixtures of these
components.
15. Gas-generating substance according to claim 3, wherein the
smell-intensive gases comprise a mercaptan.
16. Gas-generating substance according to claim 1, further
comprising a porosity generator selected from the group consisting
of ammonium hydrogencarbonate, acetone dicarboxylic acid,
azoiso-butyronitrile and hollow plastics spheres.
Description
[0001] The invention relates to gas-generating substances, in
particular for gas generators in belt tighteners and inflatable
air-bags for protecting the occupants of motor vehicles against
injuries.
[0002] With the gas generators currently used for inflatable
air-bags, a gas charge in tablet or disc form or as granules or
e.g. in noodle form is used as a combustible gas-evolving material.
During burn-off, this gas charge generates the useful or compressed
gas for the inflation of the air-bag. The disadvantage of the
combustion of solid gas-evolving materials is the extremely high
amount of slag produced during the combustion, which may make up
more than 50% of the gas charge material used. Because of the slag
and dust formed during the combustion, complicated filter stages
are required in the gas generator in order to retain slag and dust
particles. Otherwise the air-bag would be damaged during the
discharge of these particles and the occupants may be exposed to
danger.
[0003] As an alternative to these gas charges, generators
containing compressed gases or air exist. Very high charging
pressures are required for the formation of a sufficient gas
volume, since cooling takes place during the outflow of the gases
and no increase in volume is achieved through exothermic reactions
as in the case of solid mixtures. In order to offset the cooling, a
solid propellant fuel is frequently used, which ensures the
operation of the gas generator merely through the heat of reaction
during its burn-off and the additional gas evolution.
[0004] The invention is based on the object of providing a
gas-evolving material for a gas generator, in particular for a belt
tightener for an inflatable air-bag for protecting the occupant of
a motor vehicle against injuries, where slag retention equipment is
not required for the gas-evolving material.
[0005] The achievement of the aforementioned object consists in a
mixture of laughing gas as oxidising agent and one or more fuels
that are solid under the usual conditions (room temperature and
standard pressure). Used as a gas-evolving material is laughing gas
(N.sub.2O) as oxidising agent in combination with solid fuels or
mixtures which react after ignition in a controlled manner in the
combustion chamber to form slag-free or largely slag-free gaseous
reaction products. The pressurised laughing gas is ignited together
with the solid fuels by an ignition device containing an ignition
charge. Use may be made as an ignition charge, for example, of an
exploding wire or an ignition bridge, optionally with reinforcement
with a booster charge, to produce a particle-rich, hot flame.
[0006] The ignition fumes and hot combustion gases ignite the
gas/solid mixture. The latter burns in the combustion chamber
without solid particles remaining. Filter stages that are
positioned before at least one outlet opening of the gas generator
housing wall may therefore be dispensed with when the gas/solid
mixture according to the invention is used. If filter stages are
provided, the latter serve exclusively cooling purposes. The
cooling may also be carried out in another manner, however, by, for
example, fitting downstream of the combustion chamber a
distribution compartment of the housing, from which the combustion
gases pass to the outside via at least one outlet opening.
[0007] According to the invention gases or gas mixtures with low
intake pressure are proposed, which, as a result of exothermic
conditions, produce a manifold increase in volume on burn-off and
require no filters of any kind. The gas or gas mixture usable
according to the invention consists of the oxidising agent. In
order to avoid high intake pressures, oxygen or air is dispensed
with as oxidising agent. In dinitrogen monoxide (laughing gas)
there exists a gas which may be easily liquefied (critical
pressure: 72.7 bar, critical temperature: 36.4.degree. C.). The
oxidising capacity is twice as high as that of air and in contrast
to pure oxygen or air, laughing gas behaves up to at least
200.degree. C. as an inert gas, as a result of which quiescent
oxidising processes are prevented even during storage at high
temperature. Nitrogen monoxide (NO/N.sub.2O, critical pressure 64
bar, critical temperature -93.degree. C.) may also be used in a
mixture with laughing gas or as a gaseous oxidising agent on its
own. In order to control the reactivity of the gases, inert gases
(carbon dioxide, air, helium, neon, argon) may be added. The use of
nitrogen monoxide has the advantage that there is no formation of
condensed portions which first have to evaporate during the
burn-off reaction. Additions of smell-intensive gases such as e.g.
mercaptans in small amounts may make a rapid detection of leaks
possible. The addition of e.g. vanillin improves the smell
properties of the burn-off fumes in the application case.
[0008] According to the invention, used as fuels are polymers from
the group of the hydrocarbons, such as ethylene, propylene,
isoprene, styrene, as well as those which may also contain oxygen
and are derived from e.g. carboxylic acids such as polyvinyl
acetates, polymethacrylates, polyterephthalates and other
polyesters, polyethers, polycarbonates, and also polyoxymethylene,
oligo- and polysaccharides such as sugar, cellulose, starch,
polyvinyl acetals or polyvinyl alcohols. In addition, however,
further polymers of different compositions are also usable,
provided the reaction products do not contain any dangerous
components in an inadmissible amount, such as e.g. HCl, HCN, HF or
phosgene. Explosive substances may also be used as additional
reactive components of the fuels. Examples are nitroguanidine
(NiGu), derivatives of tetrazole such as 5-aminotetrazole,
5-aminotetrazole nitrate, bistetrazole amine or bistetrazole,
aminoguanidine nitrate, diaminoguanidine nitrate, triaminoguanidine
nitrate, guanidine nitrate, dicyanodiamidine nitrate,
diaminoguanidine azotetrazolate, nitrotriazolone, dicanediamidine
nitrate, hexogen, octogen. The following may be used, for example,
as further fuels: urea, organic acids (e.g. fumaric acid, ascorbic
acid, oxalic acid), cork, wood, metals (e.g. aluminium, titanium)
and non-metals (e.g. boron, silicon), nitrides, azides or inorganic
benzene (B.sub.3N.sub.3). The fuels may be applied in the form of
powder, granules, pressings such as e.g. tablets, or in the case of
polymers e.g. also as cut fibres or twisted fibres, mats, woven
fabrics, porous foams e.g. of polyurethanes. To control the
burn-off, the specific embodiments may be surface-treated by being
impregnated or mixed with liquids or pasty substances
(inhibitors).
[0009] Further additives catalysts may be used, for example
ferrocene and derivatives, iron or copper acetylacetonate and/or
oxidising agents such as, for example, nitrates of alkali and
alkaline earth elements, perchlorates of alkali and alkaline earth
elements, ammonium nitrate, ammonium perchlorate, zinc peroxide,
perborates, peroxodisulphates, permanganates, tin dioxide,
manganese dioxide, oxidising agents derived from the nitramines and
mixtures of these components and/or porosity generators, such as
for example ammonium hydrogencarbonate, acetone dicarboxylic acid,
azoisobutyronitrile and/or hollow plastics spheres.
[0010] The ratio by weight of the fuels to dinitrogen monoxide is
preferably adjusted in such a way that a non-combustible gas
mixture is obtained after the reaction. Accordingly the ratio by
weight of the fuels to dinitrogen monoxide should be adapted to the
stoichiometric proportions of a (where possible) complete
combustion. Dinitrogen monoxide is therefore used to advantage in a
slight excess, referred to the fuel. The reaction products then
consist substantially of gaseous substances (CO.sub.2, H.sub.2O and
N.sub.2). The gas/solid systems described according to the
invention produce, according to how they are chosen, residue-free,
almost CO- and NO.sub.x-free, reaction products, with the burn-off
property being controllable according to the nature, proportion by
weight, geometry and configuration of the fuel.
[0011] The invention will be described in detail below through
examples, without however limiting it:
EXAMPLES
[0012] All the tests are carried out in a sealed pressure vessel
with a volume of approx. 120 ml. The ignition is performed
electrically with 150 mg of a boron/potassium nitrate mixture as
booster. The laughing gas is fed into the vessel by means of a
compressor. The weighed portion of laughing gas may be determined
by weighing of the vessel before and after the charging. The
internal pressure in the vessel comes after the feeding to approx.
4 Mpa. The solid selected is weighed into the vessel prior to the
charging with laughing gas. The pressure measurement is carried out
in the vessel by piezoelectric pressure elements. Maximum pressure
(p.sub.max), pressure increase time (.DELTA.t) and time until
maximum pressure(t.sub.pmax)is reached are measured. In Example 1
the behaviour of the laughing gas without additional fuel is shown
(see Table 1). Heating and pressure increase takes place in the
vessel due to the ignition, which pressure increase however differs
significantly from the burn-off behaviour in the presence of
solids, as Examples 2-4 show. In Examples 2-4 the burn-off
behaviour of various materials such as polystyrene, nitroguanidine
and starch is represented. A summary of the results is given in
Table 1.
1TABLE 1 Summary of results of Examples 1-4 Weighed Weighed portion
Ex- portion laughing p.sub.max .DELTA.t t.sub.pmax ample Solid
solid [g] gas [g] [Mpa] [ms] [Mpa] 1 -- -- 11 42 11.2 15.4 2 Poly-
1.1 11 62 2.2 7.1 styrene 3 Nitroguani- 1.1 11 69 1.1 4.4 dine 4
Starch 1.1 11 64 4.2 11.5 (flour)
[0013] In Examples 5-9 the influence of various make-ups and
geometries of the solid on the burn-off characteristics in the
pressure vessel is shown. Two solids are used, first of all starch
in various modifications, here characterised by the particle
diameter, and secondly nitroguanidine as a loose powder with a
grain size of approx. 50 .mu.m and as tablet with a diameter of 7
mm and a depth of approx. 2.3 mm. A summary of results is given in
Table 2.
2TABLE 2 Summary of results of Examples 5-9 p.sub.max t.sub.pmax
Example Solid Geometry [Mpa] .DELTA.t [ms] [Mpa] 5 Starch Sphere D:
63.7 4.2 11.6 1-2 .mu.m 6 Starch Sphere D: 66.4 7.01 21.9 approx.
250 .mu.m 7 Starch Sphere D: 61.7 9.4 29.9 approx. 1 mm 8
Nitroguani- Powder 68.6 1.1 4.4 dine grain size approx. 50 .mu.m 9
Nitroguani- Tablet D 60.1 10.7 38.5 dine 7 mm, D 2.3 mm
[0014] Very good estimates of gas composition and combustion
temperatures are obtained by means of thermodynamic calculations.
In Examples 10-12 a thermodynamic calculation is carried out with
the ICT code for polystyrene, nitroguanidine and starch. It is
based in each case on a solid-laughing gas mixture of 9 to 91 wt %.
A summary of the results is given in Table 3.
3TABLE 3 Summary of results of Examples 10-12 Combustion
temperature N.sub.2 CO.sub.2 H.sub.2O O.sub.2 CO NO.sub.x Example
[K] [vol. %] [vol. %] [vol. %] [vol. %] [vol. %] [vol. %] 10 4075
63.1 21.2 10.4 5.2 <0.001 0.06 11 2710 64.9 2.4 5.0 27.5
<0.001 0.14 12 3181 61.2 9.8 8.2 20.6 <0.001 0.11
* * * * *