U.S. patent application number 09/756627 was filed with the patent office on 2001-05-10 for device containing pyrotechnic material and method of manufacturing said device.
This patent application is currently assigned to TRW Occupant Restraint Systems GmbH & Co. KG. Invention is credited to Gabriel, Wolfgang, Hudelmaier, Karl, Modinger, Thomas.
Application Number | 20010000862 09/756627 |
Document ID | / |
Family ID | 8055988 |
Filed Date | 2001-05-10 |
United States Patent
Application |
20010000862 |
Kind Code |
A1 |
Gabriel, Wolfgang ; et
al. |
May 10, 2001 |
Device containing pyrotechnic material and method of manufacturing
said device
Abstract
The present invention relates to a device containing pyrotechnic
material, having a housing surrounding the pyrotechnic material,
the device being wherein the housing is formed entirely from glass
and contains at least one metal duct having a spark gap or a
heating wire.
Inventors: |
Gabriel, Wolfgang; (Alfdorf,
DE) ; Hudelmaier, Karl; (Alfdorf, DE) ;
Modinger, Thomas; (Alfdorf, DE) |
Correspondence
Address: |
Tarolli, Sundheim, Covell,
Tummino & Szabo L.L.P.
1111 Leader Building
526 Superior Avenue
Cleveland
OH
44114-1400
US
|
Assignee: |
TRW Occupant Restraint Systems GmbH
& Co. KG
|
Family ID: |
8055988 |
Appl. No.: |
09/756627 |
Filed: |
January 8, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09756627 |
Jan 8, 2001 |
|
|
|
09292546 |
Apr 15, 1999 |
|
|
|
Current U.S.
Class: |
102/202.5 |
Current CPC
Class: |
F42B 3/11 20130101; B60R
2021/26082 20130101; B60R 22/4628 20130101; F42B 3/28 20130101;
C06C 9/00 20130101; B60R 21/2644 20130101; B60R 21/264
20130101 |
Class at
Publication: |
102/202.5 |
International
Class: |
F42B 003/10 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 20, 1998 |
DE |
298 07 096.0 |
Claims
What is claimed is:
1. A device containing a pyrotechnic material, comprising a housing
surrounding the pyrotechnic material, wherein the housing is formed
entirely from glass, the housing containing at least one metal duct
comprising a spark gap or a heating wire.
2. The device according to claim 1, wherein the device is an
igniter for a gas generator.
3. The device according to claim 2, wherein the heating wire or the
spark gap is connected with the pyrotechnic material.
4. The device according to claim 2, wherein the pyrotechnic
material comprises a primary charge and a booster charge.
5. The device according to claim 1, wherein the device is a gas
generator for a safety arrangement in motor vehicles.
6. The device according to claim 5, wherein the safety arrangement
is a belt tensioner unit or an airbag module.
7. The device according to claim 1, wherein the pyrotechnic
material is solid, liquid or gaseous.
8. The device according to claim 1, wherein the housing has at
least one opening which is closed by a sealing means, the sealing
means altering its physical condition, its structure or its volume
as a result of an action of heat from the exterior below the
self-ignition temperature of the pyrotechnic material in such a way
that the opening is exposed.
9. The device according to claim 8, wherein the sealing means is a
low-melting-point metal alloy or a liquid contained in a closed
glass container, the glass container being introduced into the
opening.
10. A method of manufacturing a device containing a pyrotechnic
material, wherein the method comprises the steps of: (a) providing
a glass bulb having at least one opening; (b) introducing the
pyrotechnic material and at least one metal duct comprising a spark
gap or a heating wire into the glass bulb; (c) closing the opening
of the glass bulb forming a glass housing completely surrounding
the pyrotechnic material and containing the metal duct comprising
the spark gap or the heating wire.
11. The method according to claim 10, wherein the glass bulb is
heated in the region of the opening until the glass softens, and
the opening is closed by sealingly melting or pressing.
12. The method according to claim 11, wherein the pyrotechnic
material is cooled during heating.
13. The method according to claim 11, wherein the heated area of
the glass bulb is arranged at a distance from the pyrotechnic
material, the distance being selected such that a cooling of the
pyrotechnic material may be dispensed with.
14. The method according to claim 10, wherein the glass bulb has a
narrowed cross-section in the region of the opening.
15. The method according to claim 14, wherein the glass bulb is
heated, pulled apart and sealingly melted in the region of the
narrowed cross-sectional portion.
16. The method according to claim 10, wherein prior to introducing
the pyrotechnic material, the metal duct comprising the spark gap
or the heating wire is introduced into the glass bulb and the glass
bulb is closed in the region of the metal duct.
17. The method according to claim 10, wherein at least part of the
pyrotechnic material surrounds the spark gap or the heating wire,
the metal duct comprising the spark gap or the heating wire and the
part of the pyrotechnic material surrounding the spark gap or the
heating wire is introduced into the glass bulb and the glass bulb
is closed in the region of the metal duct.
18. The method according to claim 10, wherein the pyrotechnic
material is introduced into the glass bulb and wherein subsequently
the metal duct comprising the spark gap or the heating wire is
introduced into the glass bulb and the glass bulb is closed in the
region of the metal duct.
19. The method according to claim 10, wherein the glass bulb is a
glass tube having a first opening and a second opening located
opposite the first opening, wherein the metal duct comprising the
spark gap or the heating wire is introduced into the glass tube
through the first opening and the glass tube, in the region of the
first opening, is heated up to softening and closed and wherein
subsequently the pyrotechnic material is introduced into the glass
tube through the second opening and the glass tube, in the region
of the second opening, is heated up to softening and closed.
20. The method according to claim 19, wherein the narrowed
cross-sectional portion is arranged in the region of the second
opening.
21. The method according to claim 19, wherein the glass bulb
obtainable by introducing the metal ducts and closing the first
opening is provided as a prefabricated component.
22. The method according to claim 10, wherein the device containing
the pyrotechnic material is an igniter in a gas generator for a
safety arrangement in motor vehicles.
Description
1. The present invention relates to a device containing pyrotechnic
material, comprising a housing surrounding the pyrotechnic
material, and a method of manufacturing the device. In particular,
the invention relates to a gas generator for a safety arrangement
in motor vehicles or an igniter for such a gas generator.
BACKGROUND OF THE INVENTION
2. The gas generators and igniters currently on the market
generally have a housing of stainless steel, aluminum or plastic.
In fact in the igniters for gas generators, a high expenditure is
necessary in order to produce these in a fluid-tight and gas-tight
construction. In most cases, the metal ducts for the connecting
cables of the igniters are cast integral into a metal ring with
glass and the metal ring is connected by means of a welding process
with the remaining housing parts of the igniter.
3. Even an employment of plastic housings can not always ensure the
gas-tight and fluid-tight construction of the igniter. Owing to the
plurality of the required process steps, the production of the
known igniters is additionally extremely cost-intensive.
SUMMARY OF THE INVENTION
4. The present invention provides a device containing pyrotechnic
material, in particular an igniter for a gas generator which is
absolutely gas-tight and fluid-tight, has a lower weight compared
with the known igniters and owing to the use of a continuous
manufacturing process can be produced at a more favorable cost.
According to the invention, for this a device containing
pyrotechnic material is provided, comprising a housing surrounding
the pyrotechnic material, which device is wherein the housing is
formed from glass and contains at least one metal duct with a
heating wire or a spark gap.
5. The pyrotechnic material can be solid, liquid or gaseous.
Preferably the device is an igniter for a gas generator for use in
a safety device for motor vehicles, which contains one or more
heating wires or a spark gap for igniting the pyrotechnic material.
The pyrotechnic material can comprise a primary charge and a
booster charge. The primary charge takes up in an optimum manner
the thermal energy arising through the activation of the igniter by
means of a current impulse and ignites the booster charge. The
booster charge provides the necessary amount of energy-rich hot
particles to ignite the propellant usually contained in the gas
generator.
6. A particularly preferred embodiment of the device according to
the invention contains an arrangement by which in the case of an
undesired thermal action from the exterior, for example when the
vehicle catches fire, an opening is exposed and thereby a
controlled outflow can be ensured of the gas released by the
self-ignition of the pyrotechnic material. This arrangement
preferably comprises a material which is crystalline or liquid at
room temperature and is introduced at a suitable point into the
glass housing of the device. The crystalline or liquid material
alters its structure, its physical condition or its volume below
the self-ignition temperature of the pyrotechnic material in such a
way that when the undesired thermal action from the exterior
occurs, the arrangement exposes the opening in the housing of the
device which is closed by the arrangement.
7. The arrangement can comprise in particular an opening formed in
the glass housing of the device, the opening being closed by a
sealing means which may be formed particularly preferably from a
low-melting-point metal alloy. The sealing means may further be a
liquid contained in a closed glass container, the glass container
being introduced in the opening and integrally connected with the
glass housing.
8. The device according to the invention can also be a gas
generator for a safety arrangement in vehicles, which generator can
be used in particular in belt tensioner units or airbag
modules.
9. A further subject matter of the invention is a method of
manufacturing a device containing a pyrotechnic material, the
method comprising the following steps:
10. (a) providing a glass bulb having at least one opening;
11. (b) introducing the pyrotechnic material and the at least one
metal duct with the spark gap or the heating wire into the glass
bulb;
12. (c) closing the at least one opening of the glass bulb forming
a glass housing completely surrounding the pyrotechnic material and
containing the metal duct.
13. In a preferred embodiment of the method according to the
invention, first the metal duct with the spark gap or the heating
wire can be introduced into the glass bulb through a first opening,
the glass bulb can be heated in the region of the metal duct up to
softening of the glass material and be closed in a gas-tight and
fluid-tight manner for example by pressing or squeezing the
softened glass. Glass bulbs having melted-in metal ducts and the
associated heating wires or spark gaps may also be utilized in the
form of already prefabricated units. Thereafter, the pyrotechnic
material is introduced into the glass bulb through a further
opening and this opening is likewise closed in a gas-tight and
fluid-tight manner. The closing may be done for example by
sealingly melting, pressing or squeezing. The glass bulb is
preferably heated up to softening near the region of the opening
and is pulled apart so as to produce a reduction in cross-section
of the opening and to facilitate the subsequent process of
sealingly melting or squeezing off. In a particularly preferred
embodiment the glass bulb already has a narrowed cross-section in
the region of the further opening.
14. The pyrotechnic material may be cooled beforehand in order to
avoid self-ignition. However, selecting a suitable distance between
the region to be heated and the pyrotechnic material may make the
cooling of the pyrotechnic material unnecessary because of the low
thermal conductivity of glass. The device thus produced comprises
an integral glass housing which completely surrounds the
pyrotechnic material and into which the metal ducts for the
connecting cables of the igniter are melted in like in the known
halogen bulbs. The device is therefore absolutely gas-tight and
fluid-tight.
15. In a further embodiment of the method according to the
invention, the spark gap or the heating wire is surrounded by at
least part of the pyrotechnic material, for example in the form of
a squib containing the primary charge. The metal duct with the
spark gap or the heating wire and the part of the pyrotechnic
material surrounding the spark gap or the heating wire is then
introduced into a tubular glass bulb and the glass bulb is closed
in the region of the metal duct in the manner as described above. A
self-ignition of the pyrotechnic material is avoided preferably by
suitably selecting the distance between the pyrotechnic material
and the heated area of the opening. If required, additional
pyrotechnic material may be supplied to the glass bulb through a
further opening and the opening may thereafter be closed by
sealingly melting, pressing or squeezing, as described above.
16. It is furthermore possible to introduce first the pyrotechnic
material and thereafter the metal duct with the spark gap or the
heating wire into the glass bulb provided with an opening and then
to close the opening in the region of the metal duct in the manner
as described above. For this purpose, for example a glass bulb is
provided, which is filled with the pyrotechnic material. Then the
metal ducts, equipped with a heating wire or a spark gap, for the
connecting cables are introduced into the glass bulb. In this case
as well, the heating wire or the spark gap can already be
surrounded by a squib containing the primary charge. Thereafter,
the glass bulb containing the pyrotechnic material may be cooled
intensively by means of liquid air or liquid nitrogen and the glass
bulb may be closed by melting. The cooling step may be dispensed
with if a suitable distance is kept between the pyrotechnic
material and the heated area. This method, too, ensures a totally
gas-tight and fluid-tight connection of the components of the
igniter according to the invention.
17. If an acceleration sensor arranged in a vehicle detects an
accident, the igniter connected electrically with the sensor is
activated. The current impulse originating from the sensor causes a
burning through of the heating wire or the jumping of a spark in
the spark gap. Thereby, the pyrotechnic material or preferably the
primary charge surrounding the heating wire is ignited. This
primary charge in turn ignites the booster charge contained in the
glass bulb. The ignition of the primary charge and/or of the
booster charge causes a distinct pressure increase to occur inside
the glass bulb, which causes the latter to burst. In this way, the
hot particles released by the burning of the booster charge can
strike onto a pyrotechnic propellant contained in the gas generator
and can cause it to ignite.
18. The same mode of operation occurs if, instead of the igniter,
the gas generator is constructed according to the invention with a
glass housing. In this case, the ignition of the pyrotechnic
material contained in the gas generator causes a pressure increase
which causes the gas generator housing to burst. The hot gases
produced by the burning of the pyrotechnic material are thus
released and can actuate the safety arrangement, for example a belt
tensioner or airbag.
BRIEF DESCRIPTION OF THE DRAWINGS
19. Advantageous embodiments of the invention will be apparent from
the following description, in which reference is made to the
enclosed drawings in which:
20. FIG. 1 is a diagrammatic view of an igniter according to the
invention;
21. FIG. 2 is a cross-sectional view of an igniter according to the
invention;
22. FIG. 3 shows a gas generator according to the invention;
23. FIG. 4 shows an igniter with an arrangement for exposing an
opening;
24. FIG. 5 shows a gas generator with an arrangement for exposing
an opening; and
25. FIG. 6 is a cross-sectional view of a gas generator with an
igniter according to the invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
26. The igniter shown in FIGS. 1 and 2 comprises a housing 10 of
glass. Metal ducts 14 are melted into the glass bulb or glass
housing 10 in a gas-tight and fluid-tight manner. At the end of the
metal ducts projecting into the housing, a heating wire or a spark
gap 16 is arranged. The heating wire or the spark gap 16 is
surrounded by a primary charge 18. In the housing in addition a
booster charge 20 can also be arranged, which receives and boosts
the energy released by the primary charge 18 in the case of
activation of the igniter.
27. If the igniter is activated by a current impulse originating
from an acceleration sensor (not shown here), the heating wire or
the spark gap 16 firstly ignites the primary charge 18 which in
turn causes the burning of the booster charge 20. Through the
burning of the booster charge 20 and/or of the primary charge 18, a
pressure increase occurs in the housing 10. Through this pressure
increase, the housing 10 bursts and releases the energy-rich, hot
particles formed by the burning of the booster charge.
28. The gas generator illustrated in FIG. 3 basically has the same
structure as the igniter shown in FIGS. 1 and 2. The housing 10 of
the gas generator is likewise formed from glass. Metal ducts 14 are
melted into the glass bulb or glass housing 10 in a gas-tight and
fluid-tight manner, which at their end projecting into the gas
generator have a heating wire or a spark gap 16. The heating wire
or the spark gap 16 are surrounded by a squib 22 which can contain
a primary charge and also in addition a booster charge (not shown
here). In addition a propellant 24 is introduced into the glass
housing 10 of the gas generator, the activation of which propellant
24 leads to a bursting of the glass housing 10 and hence to a
release of the hot gases formed by the burning of the propellant
24. By means of these hot gases, a safety arrangement, for example
a belt tensioner unit or an airbag module, can be actuated.
29. FIG. 4 shows an igniter which basically has the same structure
as the igniter illustrated in FIGS. 1 and 2. In the embodiment
illustrated here, an opening 26 is provided in the igniter housing
10 formed from glass, which opening 26 is closed by a sealing means
28. The sealing means 28 has the characteristic that with an action
of heat from the exterior, below the self-ignition temperature of
the pyrotechnic material introduced into the igniter, for example
of the primary charge 18 or of the booster charge 20, it alters its
structure, its physical condition or its volume and thereby exposes
the opening 26. As sealing means, for example a low-melting-point
metal alloy can be used. The exposing of the opening ensures that
the gases developing as a result of a self-ignition of the
pyrotechnic material can flow away in a controlled manner.
30. The gas generator shown in FIG. 5 likewise has the opening 26
provided in the housing 10 formed from glass. As described above,
this opening is closed by a sealing means 28, for example a
low-melting-point metal alloy. The opening 26 or the sealing means
28 can be arranged at any desired point on the housing 10. It is
also conceivable that a thermal action from the exterior and the
change to the structure, the physical condition or the volume of
the sealing means connected therewith, leads not only to an
exposing of the opening 26 but also to a partial destruction of the
housing 10. Thereby, the surface area of the opening available for
the outflow of the gas produced as a result of the self-ignition of
the propellant is enlarged. In the housing 10 also a plurality of
openings 26, closed by the sealing means 28, can be provided.
31. Finally, FIG. 6 shows an example for application of a gas
generator including an igniter according to the invention inserted
in the gas generator. The gas generator illustrated here comprises
a housing 30 formed of conventional materials such as aluminum or
steel and a base part 32 closing off the housing. The base part may
be made of plastic. In an upper portion of the base part 32 facing
the interior of the housing 30, an O-ring 34 is arranged which
holds the housing 30 in position in the nature of a latch. Further
latching means may be provided on the outer periphery of the base
part 32 for holding the housing in place.
32. Further, an igniter according to the invention is inserted in
the upper part of the base part 32, between the O-ring 34. This
igniter has the same structure as the igniter shown in FIGS. 1 and
2, i.e. it consists of a housing 10 which is entirely formed from
glass and has metal ducts 14 melted into it in a gas-tight and
fluid-tight manner. The metal ducts 14 comprise a heating wire 16
at their ends projecting into the glass housing 10 of the igniter.
The heating wire may also be replaced by a spark gap in the known
manner. The heating wire 16 is surrounded by a primary charge 18
which in turn is in contact with a booster charge 20. At their ends
emerging from the glass housing 10 the metal ducts 14 are connected
with the connecting cables 36 for the igniter.
33. The gas generator illustrated in FIG. 6 may be used in belt
tensioner units, for example. When the igniter is activated via the
igniter connecting cables 36, the heating wire 16 will fuse and
thus ignite the pyrotechnic material 18, 20 contained in the glass
housing 10 of the igniter. The increase in pressure brought about
by the burning of the pyrotechnic material 18, 20 causes the glass
bulb of the igniter to burst and releases the housing 30 of the gas
generator from its locked position. The displacement of the housing
30 may be transferred in a known manner to a linear drive for a
belt tensioner via a shoulder 38 arranged on the outer periphery of
the housing 30.
34. Use of the igniter illustrated here is however not limited to
gas generators for belt tensioner units. Rather, the igniter
according to the invention may be utilized in any one of the known
gas generators for safety arrangements, for instance in gas
generators for driver's side impact protective device, front
passenger impact protective devices and side impact protective
devices.
35. To produce the device according to the invention or the igniter
according to the invention, preferably a glass tube is provided
which has a first opening and a second opening located opposite the
first opening. The metal ducts, which preferably consist of
tungsten or a tungsten alloy, are then introduced into the glass
tube through the first opening with the heating wire or forming a
spark gap, and the glass tube is heated in the region of the first
opening until the glass softens, and is pressed so as to melt the
metal ducts into the glass tube in a gas-tight and fluid-tight
manner. The glass tube including the metal ducts melted into it may
also be provided as a prefabricated component, such as is known,
for example, from the production of halogen bulbs.
36. When the glass tube or glass bulb containing the metal ducts
has been produced, the pyrotechnic material is introduced into the
glass bulb through the second opening. The introduction of the
pyrotechnic material may be performed in a plurality of steps which
may be interrupted by drying stages. In this way it is also
possible to introduce different pyrotechnic materials and to make
the characteristics of the device suitable for any specifically
desired purpose of application. Finally, the glass bulb containing
the pyrotechnic material is sealingly melted in the region of the
second opening. Preferably, the glass bulb already has a narrowed
cross-section in this region, so that the step of sealingly melting
may be effected by heating and pulling the glass bulb apart in the
region of the narrowed cross-section. When proceeding in this
manner, a cooling of the remaining portions of the glass bulb or of
the pyrotechnic material may be done without due to the poor
thermal conductivity of glass.
37. The igniter according to the invention ensures that the
pyrotechnic material contained inside it is sealed in an absolutely
gas-tight and fluid-tight manner and thus increases the functional
reliability of the particular gas generator or safety arrangement
concerned. At the same time, the application of a simplified and
continuous manufacturing method allows a production of the igniter
according to the invention at a favorable cost.
* * * * *