U.S. patent application number 11/881922 was filed with the patent office on 2008-01-31 for gas generator.
This patent application is currently assigned to TRW Airbag Systems GmbH. Invention is credited to Sebastian Bierwirth, Hans-Peter Neumayer, Dieter Spitzenberger.
Application Number | 20080022880 11/881922 |
Document ID | / |
Family ID | 38921841 |
Filed Date | 2008-01-31 |
United States Patent
Application |
20080022880 |
Kind Code |
A1 |
Bierwirth; Sebastian ; et
al. |
January 31, 2008 |
Gas generator
Abstract
A gas generator, especially for a vehicle safety system, has a
pyrotechnical igniter unit (22) and a holder (14) for the igniter
unit (22). The igniter unit (22) is attached to the holder (14) in
that the igniter unit (22) and the holder (14) are encapsulated
together by one of injection molding and foaming of a plastic. The
holder (14) has at least one passage opening (30, 38) for the
plastic during the encapsulation by one of injection molding and
foaming, the at least one opening being configured in such a way as
to create a form-fitting anti-twist protection between the plastic
(34) and the holder (14).
Inventors: |
Bierwirth; Sebastian;
(Rechtmehring, DE) ; Neumayer; Hans-Peter;
(Waldkraiburg, DE) ; Spitzenberger; Dieter;
(Kraiburg, DE) |
Correspondence
Address: |
TAROLLI, SUNDHEIM, COVELL & TUMMINO L.L.P.
1300 EAST NINTH STREET, SUITE 1700
CLEVEVLAND
OH
44114
US
|
Assignee: |
TRW Airbag Systems GmbH
|
Family ID: |
38921841 |
Appl. No.: |
11/881922 |
Filed: |
July 30, 2007 |
Current U.S.
Class: |
102/530 ;
102/202.14 |
Current CPC
Class: |
B60R 21/2644 20130101;
B60R 2021/26029 20130101; B60R 2021/26076 20130101 |
Class at
Publication: |
102/530 ;
102/202.14 |
International
Class: |
C06D 5/00 20060101
C06D005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 31, 2006 |
DE |
10 2006 035 584.9 |
Claims
1. A gas generator, especially for a vehicle safety system, having
a pyrotechnical igniter unit (22) and a holder (14) for said
igniter unit (22), said igniter unit (22) being attached to said
holder (14) in that said igniter unit (22) and said holder (14) are
encapsulated together by one of injection molding and foaming of a
plastic, said holder (14) having at least one passage opening (30,
38) for said plastic during said encapsulation by one of injection
molding and foaming, said at least one opening being configured in
such a way as to create a form-fitting anti-twist protection
between said plastic (34) and said holder (14).
2. The gas generator according to claim 1, wherein said passage
opening (30) is out-of-round.
3. The gas generator according to claim 1, wherein said passage
opening (30) has a notch (32) protruding laterally outwards.
4. The gas generator according to claim 1, wherein several passage
openings (30, 38) are provided.
5. The gas generator according to claim 1, wherein a central
passage opening (30) is provided.
6. The gas generator according to claim 1, wherein said holder (14)
is a section of an outer housing (10) of said gas generator.
7. The gas generator according to claim 1, wherein igniter contacts
(24) of said igniter unit (22) protrude through said holder
(14).
8. The gas generator according to claim 7, wherein said igniter
contacts (24) are part of said igniter unit (22) and form a
prefabricated unit together with said igniter unit (22).
Description
TECHNICAL FIELD
[0001] The present invention relates to a gas generator, especially
for a vehicle safety system, having a pyrotechnical igniter unit
and a holder for the igniter unit, the igniter unit being attached
to the holder in that the igniter unit and the holder are
encapsulated together by injection molding or foaming.
BACKGROUND OF THE INVENTION
[0002] Gas generators are used especially for vehicle occupant
restraint systems in the form of airbags or belt tensioners.
Various types of gas generators exist, namely, purely pyrotechnical
generators, compressed gas generators in which the pressurized gas
is released by the igniter unit, or else hybrid gas generators. The
igniter unit is a hermetically sealed, prefabricated unit and it
has to be directly or indirectly coupled to the outer housing of
the gas generator in a fixed position. Normally, a section of the
outer housing is used as the holder, that is to say, the part to
which the igniter unit is directly attached. Igniter contacts and
also the plastic used for the encapsulation by injection molding
and/or foaming protrude through a passage opening in the holder, as
a result of which sections of the igniter unit and, at the same
time, the holder are embedded in the plastic. The plastic is
intended to attach the igniter unit to the holder and also to seal
the passage opening so that it is gas-tight as well as
moisture-tight.
[0003] The object of the invention is to make a gas generator of
the above-mentioned type even more gas-tight in the area of the
transition from the holder to the igniter unit.
BRIEF SUMMARY OF THE INVENTION
[0004] This is achieved in a gas generator, especially for a
vehicle safety system, having a pyrotechnical igniter unit and a
holder for the igniter unit. The igniter unit is attached to the
holder in that the igniter unit and the holder are encapsulated
together by one of injection molding and foaming of a plastic. The
holder has at least one passage opening for the plastic during the
encapsulation by one of injection molding and foaming, the at least
one opening being configured in such a way as to create a
form-fitting anti-twist protection between the plastic and the
holder. For gas generators employed so far, a centered, circular
passage opening was provided in the holder, which has the drawback
that the plastic and the holder only established an adhesive
connection in the twisting direction, that is to say, around the
axis of the opening. Therefore, this connection has to be handled
relatively carefully so that it does not become detached, allowing
moisture to penetrate into the gas generator. In contrast, with the
invention, in addition to the adhesive connection in the twisting
direction, a form-fitting connection is also created between the
plastic and the holder, this form-fitting connection preventing
such a detachment. The form-fitting connection between the plastic
and the igniter unit in the twisting direction is normally
established in that several igniter contacts on the back of the
igniter unit protrude into the plastic.
[0005] According to a preferred embodiment, the passage opening is
out-of-round.
[0006] Another possible configuration for the passage opening is
that it is provided with a notch protruding laterally outwards
relative to the passage opening, the notch acting as an anti-twist
protection.
[0007] As an alternative, of course, several passage openings can
be provided.
[0008] As already mentioned above, the holder is especially a
section of an outer housing of the gas generator.
[0009] The igniter contacts preferably protrude through the holder
and especially are part of the igniter unit and form a
prefabricated unit together with said igniter unit.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 shows a cross section through an embodiment of the
gas generator according to the invention,
[0011] FIG. 2 shows a top view of the holder used in the embodiment
of FIG. 1 and
[0012] FIG. 3 shows a top view of an alternative holder that can be
used in FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0013] FIG. 1 shows a pyrotechnical gas generator that has a
two-shell outer housing 10 being constituted of a pot-shaped upper
part 12 and a pot-shaped lower part 14. The pot-shaped lower part
14 has an indentation 16 shaped by deep-drawing that serves to
accommodate an igniter connector (not shown here). A combustion
chamber 20 filled with pyrotechnical propellant 18 is provided
inside the gas generator 10. In order to ignite the propellant 18,
a prefabricated igniter unit 22 is used, which is situated in the
center of the combustion chamber 20 and which has a cylindrical
head 23 filled with pyrotechnical means as well as igniter contacts
24 that form part of the igniter unit and that protrude from a
backside of said igniter unit. A lid-shaped housing 26 surrounding
the head 23 of the igniter unit 22 receives a booster charge
28.
[0014] The lower part 14 of the housing 10 is shown in FIG. 2 in a
slightly enlarged depiction. It is a deep-drawn metal part that has
a centered passage opening 30 through which the two igniter
contacts 24 can protrude. The passage opening 30 is out-of-round
since it has four lateral notches 32 protruding outwards. Although
a circular bore was made in the center of the passage opening, the
passage opening becomes out-of-round because of the notches 32. Of
course, it is also possible to have a passage opening 30 that is
oval, angular or delimited by flat sides.
[0015] The igniter unit 22 is connected to the holder 14 through
encapsulation by injection molding or foaming in that these two
parts are placed into an injection molding or foaming tool. The
inserted liquid plastic 34 penetrates into and fills up an annular
interstice between the tool--which simulates what will later be the
housing 26--and the head 23. The plastic also fills up the
interstice in the vertical direction from the head 23 to the
plateau-like elevation of the holder 14, as well as the entire
passage opening 30 along with the notches 32 and finally also the
lower indentation 16 in the holder 14, except for a receptacle for
the igniter connector that will later be connected to the igniter
contacts 24.
[0016] As a result, the igniter unit 22 and the holder 14 are
embedded in the plastic 34 so that the igniter unit 22 is connected
to the holder 14 in a fixed position.
[0017] Subsequently, the booster charge 28 is filled into the lid
26 and the unit created by injection molding and/or foaming is
inserted into the lid 26.
[0018] Consequently, in the area of the out-of-round passage
opening 30 that is provided with the notches 32 and that is
completely filled with plastic 34, a mechanical anti-twist
protection is created between the cured plastic 34 and the holder
14, this anti-twist protection preventing the plastic 34 from being
loosened or detached from the holder 14 when excessive force is
exerted from the outside.
[0019] In the embodiment according to FIG. 3, in addition to the
circular central passage opening 30, four additional passage
openings 38 are provided that are likewise filled with plastic 34
so that these passage openings 38 with their smaller cross section
create the anti-twist protection.
* * * * *