Assembly of an Inflator and a Gas Exit Tube for a Vehicle Occupant Restraint System

The invention relates to an assembly for a vehicle occupant restraint system, comprising an inflator and a gas exit tube connected gas-tight to the latter.

A vehicle occupant restraint system comprises usually an inflator, an actuating sensing system for the inflator as well as a gas bag which, when required, is translated by means of the compressed gas generated by the inflator from a folded condition into an unfolded condition in which it is able to provide protection for a vehicle occupant.

Usually, the gas generated by the inflator flows directly into the gas bag or via guide passages in a housing in which the inflator is arranged. However, restraint systems have recently become known in which the inflator needs to be arranged spaced away from the gas bag by a specific amount due to design reasons, this being the reason why the gas generated by the inflator needs to be directed into the gas bag. One example of such a vehicle occupant restraint system reads from the German Utility Model 296 05 896. In this system the inflator is connected by means of a gas exit tube to the gas bag arranged remotely therefrom.

The invention provides a connection between the gas exit tube and the inflator, which can be formed in a particularly simple manner. According to the invention, the assembly for a vehicle occupant restraint system comprises an inflator and a gas exit tube connected in a gas-tight manner thereto. The inflator is provided with an discharge portion for the gas generated by the inflator when required. The discharge portion comprises an arresting means which is formed by a circumferential groove having in cross-section a saw tooth profile with a flank perpendicular to a longitudinal axis of the discharge portion. This flank is located on the side of the groove facing the gas exit tube. The gas exit tube comprises an engaging means which engages the arresting means in an interfitting manner by means of a plastically deformed portion and secures the gas exit tube axially thereto at the inflator. By using a groove with a saw tooth profile, a reliable connection between the gas exit tube and the inflator is achieved, this connection being easy to manufacture as well as quickly and automatically to fit. Furthermore, a reliable seal between the inflator and the gas exit tube is assured. As the gas exit tube, a rigid or a flexible exit tube may be selected.

It is preferably provided for that the portion of the gas exit tube engaging the groove is plastically deformed by rolling. Rolling is a working method which can be performed with a minimum of effort. This allows to store and handle the inflator separately from the other components for a considerable portion of the fitting process, this being an advantage with respect to safety. The inflator can, due to the connection formed in a simple manner with the gas exit tube, be fitted in the vehicle at the latest possible time.

Further features of the invention are set forth in the sub-claims.

The invention will now be described with reference to two embodiments, illustrated in the enclosed drawings, in which:

FIG. 1 is a partly sectioned schematic side view of an assembly in accordance with a first embodiment of the invention;

FIG. 2 is a schematic side view of an assembly in accordance with a second embodiment of the invention;

FIG. 3 is a schematic side view of an inflator as used in the assembly shown in FIG. 2;

FIG. 4 is a schematic cross-sectional view of a first variant of the assembly shown in FIG. 2;

FIG. 5 is a schematic scrap cross-sectional view of a second variant of the assembly shown in FIG. 2;

FIG. 6 shows schematically an application for an assembly in accordance with the first embodiment of the invention; and

FIG. 7 shows schematically an application for an assembly in accordance with the second embodiment of the invention.

FIG. 1 schematically shows an assembly in accordance with a first embodiment of the invention. This assembly comprises an inflator 10 shown in a scrap view as well as a gas exit tube 12. The inflator 10 is generally tubular and provided at its axial end, depicted on the right in FIG. 1, the so-called discharge portion with orifices. The gas exit tube 12 is provided for connecting the inflator to a gas bag shown schematically in FIG. 6, this gas bag being arranged along a roof strut of a vehicle indicated schematically. When the gas bag 16 is deployed, it covers the side windows of a vehicle so that the vehicle occupants are protected in the case of a side impact. The contour of the deployed gas bag is indicated by the reference numeral 19.

As is further apparent from FIG. 1, the inflator 10 is provided with an arresting means 20 in the region of the discharge portion 15 on its outer circumference. This arresting means 20 is configured as a circumferential groove with a saw tooth profile, the flank of which perpendicular to the longitudinal axis x is arranged on the side of the groove 20 facing the orifices 14.

At its end on the left as shown in FIG. 1, the gas exit tube 12 is provided with an engaging means 22 engaging the groove 20. This engaging means 22 is embodied as a plastically deformed portion of the gas exit tube 12, the profile of which is adapted to the profile of the groove 20. Thereby, the gas exit tube 12 is secured to the inflator 10 by the engaging means 22 of the gas exit tube 12 engaging the groove 20 with an interlocking fit. At the same time the engaging means 22 of the gas exit tube 12 engaging the groove 20 forms a seal so that the inflator 10 is connected gas-tight to the gas exit tube 12. The effect of this seal is supported by a guiding portion 26 in which the gas exit tube 12 closely adjoins the outer circumference of the inflator 10. This guiding portion 26 has additionally the function of stabilising the gas exit tube 12 relative to the inflator 10 so that bending moments acting between the gas exit tube 12 and the inflator 10 are kept away to a major extent from the groove 20 and the engaging means 22 engaging therewith.

In FIG. 2, a second embodiment of the invention is shown. Unlike the first embodiment in which the gas exit tube 12 extends axially relative to the inflator 10, in this second embodiment the gas exit tube 12 extends radially relative to the inflator 10 (see also FIG. 7).

In FIG. 3, an example of an inflator 10 is illustrated as may be employed in the case of the second embodiment. The difference to the inflator 10 used in the case of the first embodiment is that the orifices 14 are no longer arranged on an appendix of small diameter, but directly on the outer circumference of the inflator. In accordance with a second embodiment it is provided for that in the region of the orifices 14 of the inflator 10 a port 30 is arranged, forming the discharge portion for the gas furnished by the inflator 10. This port is connected to the inflator 10 by means of a clip 32.

In FIG. 4, a first variant of the second embodiment of the invention is illustrated. The port 30 is arranged on the upper orifice 14 relative to the view in FIG. 4. Over the lower orifice 14 relative to FIG. 4 a sealing strip 34 is disposed. Both the sealing strip 34 and the port 30 are securely fixed by means of the clip 32 to the outer circumference of the inflator 10. This clip 32 may be tensioned by means of a schematically depicted screw 36 on the outer circumference of the inflator 10, for example.

Tests have indicated that closing off part of the orifices 14 of the inflator 10 has practically no effect on the exit time of the compressed gas generated. The gas exiting through the remaining open orifice 14 flows through the port 30 directly into the gas exit tube 12. In this variant the gas exit tube 12 is secured to the port 30 by means of an arresting means and an engaging means as is known from FIG. 1.

For the port 30 in the variant illustrated in FIG. 4, a relatively soft material may be used which due to the pressure exerted by the clip 32 adapts to the outer circumference of the inflator 10 so that without using an additional seal a gas-tight connection is attained between the port 30 and the inflator 10. In accordance with a variant (not shown) the port 30 may also be coated with a soft material so that it forms a snug gas-tight fit with the inflator 10.

In FIG. 5, a second variant of the second embodiment of the invention is illustrated. This variant differs from the variants shown in FIG. 4 by the port 30 and the clip 32 being provided integrally with each other. In the variant illustrated the clip 32 is forced on the inflator 10 by pressure.