Ammunition and explosives – Jacketed or cartridge gas generator
Reexamination Certificate
1998-07-03
2001-05-29
Swiatek, Robert P. (Department: 3643)
Ammunition and explosives
Jacketed or cartridge gas generator
C280S741000
Reexamination Certificate
active
06237498
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to an inflator, more particularly for a vehicle occupant restraint system. The invention further relates to a method of making an inflator.
BACKGROUND OF THE INVENTION
Known tubular inflators for inflating gas bags in vehicles are usually configured single-stage or two-stage. The expense of their fabrication is relatively high, this being due to the fact that totally different designs are provided for single-stage and two-stage inflators. Tubular inflators are mainly provided for restraint systems on the front passenger side since their outer geometry is best suited for accommodation in the dashboard.
One highly complicated two-stage tubular inflator configuration is evident from U.S. Pat. No. 5,033,390. In this arrangement, at the two axial ends of the inflator housing combustion chambers are provided between which two expansion spaces are arranged. These two expansion spaces separated from each other are formed by two outer disks and an intermediate disk formed integrally on an anchor adjoining the outer disks. In addition to this, elongated tubes are screwed into place axially from without, which comprise a booster charge in their interior and are connected with axial covers which seal off the two-part tubular housing at the end faces. Moreover, the tubular housing has in its interior axial stops for positioning the disks. When an inflator is to be produced which has larger or smaller combustion chambers, the housing and anchor parts need to be redimensioned. This makes the use of like parts very difficult. It will also be readily appreciated that this complicated structure makes fabricating the inflator relatively expensive. On top of this the individual parts do not lend themselves to be also put to use in single-stage inflators. The same drawbacks are exhibited by the inflator disclosed in U.S. Pat. No. 5,219,178, in which all parts inserted in the tubular housing adjoin each other axially and fix each other in position.
SUMMARY OF THE INVENTION
The invention provides an inflator the design principle of which permits simple, cost-effective manufacture of both a single-stage and a two-stage or multi-stage version. The basic principle of the invention results in a kind of modular system in which numerous parts in the single-stage or multi-stage version are the same. In addition to this, the inflator in accordance with the invention enables the inflator output to be varied by simple means without necessitating any basic change in design or a different dimensioning of the individual parts. The inflator according to the invention for a vehicle occupant restraint system comprises a tubular inflator housing including opposite end faces at which it is closed off and having radial exit ports via which the gas is able to exit the inflator, and having in its interior at least one combustion chamber packed with propellant, at least one ignition unit for igniting the propellant in the combustion chamber and at least one filter being located upstream of the exit ports. The inflator further includes a filter insert featuring an outer housing having a plurality of housing parts which at least partly surround the filter disposed in the filter insert. In a condition in which the outer housing is secured to the inflator housing, hereinafter referred to as secured condition, the outer housing, together with its housing parts, is radially secured to the inflator housing without the provision of an axial stop. The outer geometry of the outer housing and the inner geometry of the inflator housing, however, permit total insertion of the outer housing or its housing parts in the axial direction into the inflator housing to different insertion depths when the outer housing is still in a non-secured condition. Whereas in the prior art provision is always made for axial stops at the housing parts and for parts which are adapted to a specific combustion chamber size, the present invention provides for insertion of the outer housing or the housing parts of the filter insert into the inflator housing to different insertion depths without the provision of an axial stop prior to securing the outer housing and the inflator housing. The filter insert can thus be positioned within the inflator housing at any required position and subsequently secured thereto. When a single-stage inflator is to be manufactured, the insert is inserted into the inflator housing configured tubular only to such an extent that it is located at one end of the inflator. For a multi-stage inflator, practically the same inflator housing can be made use of and, where necessary, also the same insert, except for minor modifications, which is then simply inserted deeper into the inflator housing and secured thereto. Depending on whether the filter insert is located in the middle between the ends of the inflator housing or nearer to one end thereof, combustion chambers the same or different in size can be provided adjoining the filter insert. Changing the volume of the combustion chamber in this way necessitates no change to the geometry of the parts, this also applying to a single-stage inflator in accordance with the invention in which, for downsizing the output, the filter insert merely needs to be inserted deeper into the inflator housing otherwise dimensioned the same. This results in enhanced variability as regards the combustion chamber volumes and it being made easy to adapt the inflator output to specific customer requirements. High component correspondence and low number of components required result in low costs per item, while the preassembling capability of the insert facilitates assembly and helps in reducing costs.
When by contrast the volume of one or both combustion chambers needs to be changed in the case of the inflator known from U.S. Pat. No. 5,033,390, then both tubes to be assembled to form the inflator housing as well as the many axial connecting parts arranged internally need to be totally adapted.
Preferably, the entire filter insert forms a preassembled unit which is inserted in the inflator housing. But it is also possible for the filter insert to be assembled when it is already in the inflator housing. This can be done for example in that the outer housing has two end face walls which only partly surround the filter (at the end faces) and clamp the filter inbetween and which are inserted from opposite axial openings provided in the tubular inflator housing. Preferably, a press fit is provided between the inflator housing and the outer housing so as to fix the filter insert or its housing parts to some extent during insertion.
In the preferred embodiment of the invention the insert also has at least one expansion space in its interior.
When the inflator in accordance with the invention is configured as a single-stage inflator, the insert is provided, as mentioned, at one axial end of the inflator housing, it sealing off the latter from without at this end.
Another possibility of reducing the number of parts employed consists in the inflator comprising an insert with an ignition unit extending axially through the latter into the combustion chamber. The inserts with and without ignition unit hardly differ from each other. Depending on the desired installation position or the ambient circumstances, for example, the insert with the ignition unit is inserted at the side of the inflator having more facilitated access and the insert without ignition unit at the other side. As a result of this modular system various configurations can be achieved at no additional expense in design or fabrication. If the inflator in accordance with the invention is configured multi-stage, then, as mentioned, the insert is simply inserted in the inflator housing so far that it is located between two combustion chambers. If an insert is employed which is open at both end faces then the insert may serve as the filter insert for both combustion chambers. Should several filter inserts or expansion spaces be needed, then, for example, two inserts may be inserted one after the other, one of which
Adam Paul
Fink Martin
Leifheit Markus
Winterhalder Marc
Swiatek Robert P.
Tarolli, Sundheim, Covell Tummino & Szabo L.L.P.
TRW Airbag Systems GmbH & Co. KG
LandOfFree
Pyrotechnical inflator and method of making same does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Pyrotechnical inflator and method of making same, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Pyrotechnical inflator and method of making same will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2552720