U.S. patent application number 10/001241 was filed with the patent office on 2002-06-20 for gas generator for low-slag gas cartridges for motor vehicle safety.
Invention is credited to Bley, Ulrich, Brede, Uwe, Bretfeld, Anton, Havlik, Julia, Redecker, Klaus, Reiss, Heinz.
Application Number | 20020073873 10/001241 |
Document ID | / |
Family ID | 26007983 |
Filed Date | 2002-06-20 |
United States Patent
Application |
20020073873 |
Kind Code |
A1 |
Bley, Ulrich ; et
al. |
June 20, 2002 |
Gas generator for low-slag gas cartridges for motor vehicle
safety
Abstract
The invention relates to a gas generator, especially for an air
bag, having two tubes (9, 10) arranged concentrically one in the
other, the inner tube (10) forming the combustion chamber,
containing the fuel (3), and being closed by a cover plate (11) and
an end plate (12). The gas generator is especially suitable for the
use of laughing gas and has a cover plate (11) joined to an end
plate (12) by an igniter tube (7) passing through the combustion
chamber. An ignition element is disposed in the cover plate, whose
discharge opening for the ignition gases is in communication with
the igniter tube (7). A longitudinally displaceable piston (2) is
disposed in the igniter tube (7), and radial openings (6) into the
combustion chamber are disposed in the igniter tube (7). The
igniter tube (7) is connected with an outlet in the end plate
(12).
Inventors: |
Bley, Ulrich; (Furth,
DE) ; Brede, Uwe; (Furth, DE) ; Bretfeld,
Anton; (Furth, DE) ; Havlik, Julia; (Furth,
DE) ; Redecker, Klaus; (Nurnberg, DE) ; Reiss,
Heinz; (Furth, DE) |
Correspondence
Address: |
FULBRIGHT & JAWORSKI, LLP
666 FIFTH AVE
NEW YORK
NY
10103-3198
US
|
Family ID: |
26007983 |
Appl. No.: |
10/001241 |
Filed: |
November 15, 2001 |
Current U.S.
Class: |
102/530 |
Current CPC
Class: |
B60R 21/2644 20130101;
C06D 5/00 20130101 |
Class at
Publication: |
102/530 |
International
Class: |
C06D 005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 15, 2000 |
DE |
100 62 750.1 |
Sep 19, 2001 |
DE |
101 46 074.0 |
Claims
It is claimed:
1. A gas generator comprising: an inner tube and an outer tube
arranged concentrically one in the other, said inner tube forming a
combustion chamber, containing fuel and being closed with a cover
plate and an end plate; an igniter tube extending through said
combustion chamber and joining said cover plate to said end plate;
an ignition element disposed in said cover plate, said ignition
element having an outlet opening for the ignition gases in
communication with said igniter tube; a longitudinal displaceable
piston disposed in said igniter tube; said igniter tube having
radial openings into the combustion chamber disposed therin; said
igniter tube being joined in the end plate to an outlet.
2. The gas generator according to claim 1, wherein a discharge
chamber is disposed in said end plate, said outlet of said igniter
tube opening into said discharge chamber, said discharge chamber
being connected through blowout openings to an afterburning chamber
disposed between said outer tube and said inner tube.
3. A gas generator according to claim 1, wherein said piston is
joined to said cover plate with a break-away edge.
4. A gas generator according to claim 1, wherein an area for
receiving said piston is disposed in said discharge chamber behind
said discharge openings in the direction of flow.
5. A gas generator according to claim 1, wherein the number of
radial openings in said igniter tube increases toward said outlet
chamber.
6. A gas generator according to claim 1, wherein discharge openings
are disposed in said outer tube.
7. A gas generator according to claim 1, wherein said discharge
openings and said blow-out openings are closed by a membrane.
8. A gas generator according to claim 7, wherein after the ignition
of said ignition element said piston tears open the blow-out
openings.
9. A gas generator according to claim 1, further comprising cooling
elements disposed in said afterburning chamber.
10. Fuel for use in a gas chamber comprising nitrous oxide and at
least one organic substance
11. The fuel of claim 10, wherein said organic substance is
selected from the group consisting of polyethylene, starch and
paraffin.
Description
BACKGROUND AND SUMMARY OF THE INVENTION
[0001] The invention relates to a gas generator, especially for an
airbag, with two tubes arranged concentrically one in the other,
the inner tube forming the combustion chamber, containing the fuel
and being closed with a cover plate and an end plate.
[0002] Gas generators, mainly those having solid gassing charges in
the form of tablets, are required especially for the inflation of
air bags for motor vehicle safety, e.g., for drivers or passengers,
or for side air bags. These are installed in motor vehicles and are
an essential part of motor vehicle safety.
[0003] In the gas generators for inflatable collision cushions that
are used at this time, the combustible, gas developing material is
a gassing charge in tablet form, plate form, or granules. Upon
deflagration, this gassing charge produces the pressure to inflate
the collision cushion. The disadvantage of the combustion of solid
gas-generating materials consists in the rather great mount of slag
produced by the combustion, which can amount to more than 50% of
the mass of the gassing charge. Due to the formation of slag and
dust by the burn, expensive filter stages are necessary in the gas
generation in order to withhold slag and dust particles. Otherwise,
the collision cushion would be damaged by the discharge of these
particles and the occupants could be endangered. As alternatives to
these gassing charges, there are generators with compressed gases
or air. To form a sufficient gas volume, very high charging
pressures are necessary, since as the gases are released chilling
occurs, and no gain of volume is achieved by exothermic reactions
as in the case of solid mixtures. To compensate for the chilling a
solid propellant is often used, which only due to the heat produced
by its deflagration and the additional production of gas assures
the operation of this gas generator.
[0004] The present invention describes such gas generators for use
in motor vehicle interiors for filling gas bags serving for the
protection of occupants. The gas generator is characterized by the
use of nitrous oxide (laughing gas) as oxidizer and various organic
substances such as polyethylene, starch or paraffin as fuel. This
gas generating substance has already been described in WO 00/48
987.
[0005] An object of the invention is to provide an improved a gas
generator, especially for an airbag with two tubes arranged
concentrically one in the other, the inner tube forming the
combustion chamber, containing the fuel and being closed with a
cover plate and an end plate such that it is especially suited for
the use of laughing gas as a gas producing substance.
[0006] This problem is solved by the invention in that the cover
plate is joined to the end plate through an igniter tube extending
through the combustion chamber; an igniter element is disposed in
the cover plate and its opening for discharging the ignition gases
is connected to the igniter tube; and a longitudinally displaceable
piston is arranged in the igniter tube. Radial openings into the
combustion chamber are provided and the igniter tube is joined to
an outlet in the end plate.
[0007] In a preferred embodiment, a discharge chamber is provided
in the end plate, into which the outlet of the igniter tube opens
and the discharge chamber is connected to an afterburning chamber
disposed between the outer tube and the inner tube.
[0008] The piston is joined for the defined control of movement to
the cover plate preferably by a break-away edge.
[0009] To prevent the piston from blocking the discharge openings
after the ignition when it passes through the igniter tube, in a
preferred embodiment a receiver for the piston is disposed in the
discharge chamber following, in the direction of flow, the
discharge openings. A means for trapping the piston can be disposed
in this receiver.
[0010] For a more uniform ignition of the fuel, the number of the
radial openings in the igniter tube advantageously increases toward
the discharge chamber. Likewise the size of the openings can
increase.
[0011] Discharge openings are provided in the outer tube and the
gas can exit through them.
[0012] Preferably the discharge openings are closed by a membrane,
and the membrane at the discharge openings bursts due to the
movement of the piston after the ignition element ignites.
[0013] Cooling means are preferably arranged in the afterburning
element to cool the outflowing gases.
[0014] According to the invention, this gas generator if
preferentially suitable for a fuel of nitrous oxide (laughing gas)
as oxidizer and various organic substances such as polyethylene,
starch or paraffin.
[0015] In comparison with the current state of the art on the basis
of solids in the form of tablets, this solution has the advantage
of lower ejection of solids after the charge has burned. This
feature is gaining increasing importance due to safety aspects with
respect to the occupants of vehicles, especially those with health
problems such as might occur in the firing of the generators in the
case of asthmatics.
BRIEF DESCRIPTION OF THE DRAWING
[0016] The drawing is an embodiment of a gas generator according to
the invention.
DETAILED DESCRIPTION
[0017] The gas generator according to the invention is represented
in the single drawing. It can consist of the illustrated components
with the main feature of zone ignition, valve operation, fuel
containers and afterburning space for cooling.
[0018] The gas generator consists of an outer tube 9 with radial
openings 8, in which an inner tube is concentrically arranged. The
inner tube 10 is closed by a cover plate 11 and an end plate 12 at
its extremities. Cover plate 11 and end plate 12 are joined
together by an igniter tube 7. An igniter element 1 is loaded into
the cover plate 11 and its ignition gas outlet communicates with
the igniter tube 7.
[0019] In the igniter tube 7 a piston 2 is inserted, which is
joined to cover plate 11 by a breakaway edge 14. The piston 2 can
be in contact with the inner wall of the igniter tube 7 through
O-rings or sealing rings.
[0020] In the end plate 12 there is provided a discharge chamber 13
into which the igniter tube 7 leads. This discharge chamber 13 is
connected by openings to the afterburning chamber 5 between outer
tube 9 and inner tube 10.
[0021] Downstream from the discharge openings 4 an area to receive
the piston 2 is provided in the discharge chamber. Cooling elements
16 are disposed in the afterburning chamber 5.
[0022] In operation, after ignition, for example by electrical
igniters 1 as in EP 0 618 424 B1, with SINCO, for example, as an
intensifying charge as described in EP 0 809 616 A1, and with the
thermal safety device as described in EP 0 914 305 A1, a piston 2
is driven which, among other things, releases openings 6 step by
step, whereby a zoned ignition of the fuel and oxidizer mixture
3--is made possible. The fuel 3 is ideally arranged annularly
around the igniter tube 7, the fuel being held on stainless steel
meshes, for example, or combustible materials in the form of fabric
woven from fully combustible fibers such as cellulose, for example.
Another function of the piston is finally the punching out of the
blast openings 4. The opening action can be controlled by the
appropriate selection of, for example, the mass of the piston, the
distance to be traveled, or the ignition power. After the opening
action, the combustion gases enter an afterburning chamber 5. Here
an effective cooling can be achieved by suitable measures such as
bunches of wire, ceramic supports or substances that can be
vaporized or thermally decomposed, such as carbonates, oxalic acid,
oxalates, and others.
[0023] The discharge openings 8 in the igniter tube 7 can
advantageously be arranged at closer intervals toward the blast
openings 4, thereby achieving a more uniform ignition of the fuel
3.
[0024] The discharge openings 8 and the blast openings 4 can be
sealed with a membrane.
[0025] Other embodiments of the present invention will be readily
apparent to those skilled in the art and are intended to be within
the scope of the claims appended hereto.
* * * * *