U.S. patent application number 14/045851 was filed with the patent office on 2015-04-09 for autoignition for igniting gas-generative compositions used in inflator devices for protective passive restraints.
This patent application is currently assigned to ARC AUTOMOTIVE. The applicant listed for this patent is Russell Klaus Campbell, James Michael ROSE. Invention is credited to Russell Klaus Campbell, James Michael ROSE.
Application Number | 20150096653 14/045851 |
Document ID | / |
Family ID | 52776000 |
Filed Date | 2015-04-09 |
United States Patent
Application |
20150096653 |
Kind Code |
A1 |
ROSE; James Michael ; et
al. |
April 9, 2015 |
AUTOIGNITION FOR IGNITING GAS-GENERATIVE COMPOSITIONS USED IN
INFLATOR DEVICES FOR PROTECTIVE PASSIVE RESTRAINTS
Abstract
An autoignition composition for a gas generant for an airbag or
the like. The autoignition comprises a mixture of CuO as the
oxidizer in a weight percentage of 45% to 75%, and aminoguanidine
nitrate as the fuel in a weight percentage of 25% to 55%. To
increase the flame temperature of the mixture, a metal fuel such as
magnesium or aluminum can be added.
Inventors: |
ROSE; James Michael;
(Knoxville, TN) ; Campbell; Russell Klaus; (Lenoir
City, TN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ROSE; James Michael
Campbell; Russell Klaus |
Knoxville
Lenoir City |
TN
TN |
US
US |
|
|
Assignee: |
ARC AUTOMOTIVE
Knoxville
TN
|
Family ID: |
52776000 |
Appl. No.: |
14/045851 |
Filed: |
October 4, 2013 |
Current U.S.
Class: |
149/38 ;
149/92 |
Current CPC
Class: |
C06B 25/34 20130101;
C06B 33/08 20130101; C06B 33/00 20130101; C06C 9/00 20130101 |
Class at
Publication: |
149/38 ;
149/92 |
International
Class: |
C06B 25/34 20060101
C06B025/34; C06B 33/08 20060101 C06B033/08 |
Claims
1. An autoignition composition for a gas generant for inflating an
airbag or the like, said autoignition composition comprising a
mixture of CuO as the oxidizer in a weight percentage of 45% to
75%, and aminoguanidine nitrate as the fuel in a weight percentage
of 25% to 55%.
2. The autoignition composition of claim 1 using an oxygen balance
of approximately -2% which is 55% CuO by weight and 45%
aminoguanidine nitrate by weight.
3. The autoignition composition of claim 2 wherein the adiabatic
constant pressure flame temperature at 7 MPa is approximately
1793.degree. K.
4. The autoignition composition of claim 3 wherein the composition
ignites at 150.degree. C.
5. The autoignition composition of claim 1 wherein a metal fuel is
added to increase the flame temperature of the mixture.
6. The autoiginition composition of claim 5 wherein the metal fuel
is aluminum or magnesium.
7. The autoignition composition of claim 6 wherein the weight
percentage of magnesium or aluminum is less than 20%.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates generally to gas generant
compositions and, more particularly, to gas generant compositions
employed in various autoignition devices, such as vehicle occupant
passive restraint systems (airbags), fire suppressants, aircraft
escape chutes, life rafts and the like.
[0003] 2. Description of the Prior Art
[0004] Many devices, such as protective passive restraints or air
bags used in motor vehicles. escape slide chutes. life rafts, and
the like, are normally stored in a deflated state and are inflated
with gas substantially instantaneously at the time of need. Such
devices are generally stored and used in close proximity to humans
and, therefore, must be designed with a high safety factor which is
effective under all conceivable ambient conditions.
[0005] Inflation is sometimes accomplished solely by means of a gas
generative composition. At other times, inflation is accomplished
by means of a gas, such as air, nitrogen, carbon dioxide, helium,
and the like, which is stored under pressure and further
pressurized and supplemented at the time of use by the addition of
high temperature combustion gas products produced by the burning of
a gas-generative composition.
[0006] It is critical that the gas-generative composition be
capable of safe and reliable storage without decomposition or
ignition at temperatures which are likely to be encountered in a
motor vehicle or other storage environment. For example.
temperatures as high as about 107.degree. C. (225.degree. C.) may
reasonably be experienced It is also important that substantially
all the combustion products generated during use be non-toxic.
non-corrosive, non-flammable, particularly where the inflator
device is stored in a closed environment, such as a passenger
compartment of a motor vehicle.
[0007] Igniters are well known in the art for igniting
gas-generative compositions in inflators for protective passive
restraints used in motor vehicles. In a typical inflator device,
the igniter itself may be ignited either directly, or indirectly
via an intermediate or auxiliary igniter, by an electrically
activated initiator (e.g., squib) which is responsive to a sensed
impact of the motor vehicle.
[0008] Due to the emphasis on weight reduction for improving fuel
mileage in motor vehicles, inflator units are often formed form
light weight materials, such as aluminum, that can lose strength
and mechanical integrity at temperatures significantly above the
normal operating temperature of the unit. Although the temperature
required for the unit to lose strength and mechanical integrity is
much higher than will be encountered in normal vehicle use, these
temperatures are readily reached in, for example, a vehicle fire.
As the operating pressure of the standard pyrotechnics increases
with increasing temperature, a gas generator composition at its
autoignition temperature will produce an operating pressure that is
too high for a pressure vessel that was designed for minimum
weight. Moreover, the melting point of many gas generator
compositions is low enough for the gas generator composition to be
molten at the autoignition temperature of the composition, which
can result in a loss of ballistic control and excessive operating
pressures. Therefore, in a vehicle fire, for example, the ignition
of the gas generator composition can result in an explosion in
which fragments of the inflation unit are propelled at dangerous
and potentially lethal velocities.
[0009] To prevent such explosions, inflator units have typically
been provided with an autoignition propellant (sometimes
abbreviated hereinafter as "AIP") that will autoignite and initiate
the combustion of the main gas generating pyrotechnic charge at a
temperature below that at which the shell or housing of the
inflator unit begins to soften and lose structural integrity.
[0010] Some gas generator or pyrotechnic devices require a
non-chlorate low temperature autoignition material to safely ignite
the main pyrotechnic charge contained within the device when the
device is exposed to a high temperature environment or a flame.
This is especially true when the main pyrotechnic charge contains
ammonium nitrate as an ingredient. For these types of pyrotechnic
devices the required autoignition temperature of the autoignition
material is often within the range of 140.degree. C. to 160.degree.
C.
[0011] It would be desirable if an AIP composition could be
provided which satisfies the need to reduce the ignition
temperature of the propellant composition below its autoignition
temperature while, at the same time, exhibits a high degree of
stability and compatibility. The composition of the present
invention meets such need.
BRIEF SUMMARY OF THE INVENTION
[0012] The present invention is directed to an autoignition
composition comprising a mixture of cupric oxide (AKA, CuO, copper
valance 2 oxide) as the oxidizer and aminoguanidine nitrate as the
fuel. The weight percentage of CuO lies within the range of 45% to
75%, and the weight percentage of aminoguanidine nitrate lies
within the range of 25% to 55%.
[0013] If it is desired to increase the flame temperature of the
mixture, a metal such as magnesium (Mg) or aluminum (Al) can be
added to the mixture in a weight percentage of less than 20%.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a DSC (Differential Scanning calorimetry) analysis
of pure aminoguanidine nitrate; and
[0015] FIG. 2 is a DSC (Differential Scanning calorimetry) analysis
of a mixture consisting of 55% CuO by weight and 45% aminoguanidine
nitrate by weight.
DETAILED DESCRIPTION OF THE INVENTION
[0016] This invention relates to a chlorate free low temperature
autoignition composition based upon oxidizers and/or fuels that
have melting point temperatures >135.degree. C. and
<160.degree. C. In particular the present invention uses
aminoguanidine nitrate as the fuel whose melting temperature is
approximately with the range of 144.degree. C. to 147.degree. C.
With the correct selection of an oxidizer when the aminoguanidine
nitrate melts, ignition occurs. FIG. 1 shows a DSC (Differential
Scanning calorimetry) analysis of pure aminoguanidine nitrate. The
melt point (onset of endotherm) can be clearly seen at
approximately 145.degree. C.
[0017] The present invention in particular uses the oxidizer cupric
oxide (AKA; CuO, copper valance 2 oxide) with aminoguanidine
nitrate. FIG. 2 shows a DSC (Differential Scanning calorimetry)
analysis of a mixture consisting of CuO (55% by weight) and
aminoguanidine nitrate (45% by weight). The melt (endotherm) of the
aminoguanidine nitrate can be seen which is immediately followed by
a large exotherm. Hot plate test analysis of 0.5 gram sample of the
mixture confirmed ignition with a large sustained flame at
150.degree. C. Furthermore, automotive airbag inflators that use an
ammonium nitrate based main generant material were put through a
slow heating environment and all inflators benignly deployed when
the skin temperature of the inflators reached 152.degree. C.
[0018] Stoichiometric reacton equation is:
5 CuO+2 CH.sub.7N.sub.5O.sub.3.fwdarw.5 Cu 2 CO.sub.2+7 H.sub.2O+5
N.sub.2
[0019] The stoichiometric weight percentages are 59.2% CuO and
40.8% aminoguanidine nitrate. The adiabatic constant pressure flame
temperature at 7 MPa is approximately 1815.degree. K.
[0020] The preferred formulation uses an oxygen balance of
approximately -2% which is 55% CuO and 45% aminoguanidine nitrate,
by weight. This mixture's adiabatic constant pressure flame
temperature at 7 MPa is approximately 1793.degree. K.
[0021] In accordance with the present invention, the autoiginition
composition may comprise a mixture of CuO as the oxidizer in a
weight percentage in the range of 45% to 75%, and aminoguanidine
nitrate as the fuel in a weight percentage in the range of 25% to
55%.
[0022] If higher adiabatic flame temperatures are required to cause
ignition of the pyrotechnic materials contained within a gas
generator or pyrotechnic device, other metal fuels such as aluminum
or magnesium can be added. For example; 5% aluminum added to CuO
and aminoguanidine nitrate at -2% oxygen balance has an adiabatic
constant pressure flame temperature at 7 MPa of approximately
2359.degree. K, 10% added aluminum yields approximately
2889.degree. K and 15% added aluminum yields approximately
3371.degree. K. In accordance with the present invention, the
weight percentage of aluminum or magnesium preferably is less than
20% by weight.
[0023] The AIP compositions may be used in the form of powders,
granules, or compression-molded pellets. The AIP compositions are
most preferably used in the form of a solid compression-molded
mixture of the above-described components. In this regard, the
compositions will therefore most preferably include a polymeric
binder in an amount sufficient to bind the components into a solid
form (e.g., pellet). The binder will therefore typically be present
in an amount. based on the total AIP composition weight, of between
about 1.0 to about 5.0 wt. %, and preferably about 2.0 wt. %. The
preferred binders include poly(alkylene carbonates) that are
commercially available from Pac Polymers, Inc. as Q-PAC.RTM. 40, a
poly(propylene carbonate) copolymer, and Q-PAC.RTM. 25, a
poly(ethylene carbonate) copolymer, or mixtures thereof.
[0024] While the invention has been described in connection with
what is presently considered to be the most practical and preferred
embodiments, it is to be understood that the invention is not to be
limited to the disclosed embodiments, but on the contrary, is
intended to cover various modifications and equivalent arrangements
included within the spirit and scope of the appended claims.
* * * * *