Vehicle window air bag curtain

An air bag curtain, particularly for a vehicle window, comprises several tube-shaped chambers which are arranged side-by-side. The chambers are spaced from one another and can be filled with gas and have a largely circular cross-section after being filled with gas. In the effective gas-filled position, the air bag curtain extends between two lateral fastening points. The chambers, which are crossed by a tension line connecting the two fastening points with one another, are constructed with a bulge in the crossing area which results in the oval cross-section being oriented approximately in the direction of the tension line.

BACKGROUND AND SUMMARY OF THE INVENTION 
This application claims the priority of German application 197 18 203.8, 
filed Apr. 30, 1997, the disclosure of which is expressly incorporated by 
reference herein. 
The present invention relates to an air bag curtain for a vehicle window 
and the like, and more particularly, to an air bag curtain having several 
tube-shaped chambers which are arranged side-by-side, are spaced from one 
another and can be filled with gas and which have a largely circular 
cross-section after they are filled with gas. 
DE 22 22 621 A1 describes an air bag curtain which can be filled with gas 
and in which, by way of a linear connection of the two curtain sections 
disposed on one another, gas-fillable tube shaped chambers are 
constructed. In the gas-filled effective position, the chambers have 
largely the same circular cross-section along its longitudinal course. As 
a result, a maximal energy absorption capacity exists when loaded by the 
occupants. A fixing of the air bag curtain in its effective position so 
that this curtain cannot be displaced from its protective covering 
position by the impacting occupant was not considered. 
A general background of an air bag which is held in its effective position 
by additional holding devices is also found in DE 43 07 175 A1; DE 42 38 
427 A1; DE 92 11 423 U1; and DE 41 37 749 A1. 
An object of the present invention to hold an air bag curtain in a 
gas-filled manner in an effective securely protective position thereof. 
This object has been achieved in accordance with the present invention by 
providing that in the effective position, in a gas-filled manner, the air 
bag curtain extends between two lateral fastening points, and in that the 
chambers, which are crossed by a tension line connecting the two fastening 
points with one another are each constructed with a bulging in the 
crossing area which results in an oval cross-section oriented 
approximately in the direction of the tension line. 
An air bag curtain in accordance with the present invention is normally 
disposed in a gathered, stored manner along an edge of the vehicle window 
and is filled during the crash by the gas from an activated gas generator 
or gas accumulator. Thereby, the air bag is changed into its effective 
position in front of the vehicle window. The air bag can also be arranged, 
however, on the inside at the roof in the transverse direction of the 
vehicle and spread out in front of an occupant. That is, the air bag 
curtain, which in contrast to a single-chamber air bag, has individual, 
mutually gastightly separated chambers, has the advantage that the air bag 
curtain can be filled with a lower gas quantity which, in the event of a 
side impact, can be achieved particularly advantageously within a shorter 
time period and, because of the lower gas pressure, in a more protective 
manner for the occupant. Consequently, a circular gas-filled cross-section 
resulting from the boundary lines of a chamber leads to a maximal energy 
absorption capacity when the chambers are loaded by the occupants. 
So that the air bag cannot be displaced from its effective position in the 
vehicle interior in front of the vehicle window by the impacting occupant, 
the curtain sides are fastened on the vehicle body and the interior 
panelling of the vehicle so that the gas filling of the chambers creates a 
tension line between the fastening points on both sides. The air bag 
curtain is thereby tensioned between the fastening points and is held 
close to the vehicle window. 
On this tension line, the chambers are constructed with a larger width 
because of the course of the boundary lines bounding the chambers. 
Consequently, an oval cross-section of the chambers in the direction of 
the curtain surface is formed in this area by which a higher tension force 
can be generated between the fastening points without imparing the 
circular cross-sectional shape of the adjoining chamber areas. 
This individual construction of the chambers results in an optimal energy 
consumption being maintained in the impact area of the occupant as the 
result of the circular cross-sectional shape of each chamber. A maximal 
tension can nevertheless be introduced into the air bag curtain along the 
tension line by way of which the air bag curtain is securely held in its 
effective position. 
The effective position of the air bag curtain can be fixed in a 
particularly secure manner if the tension line is provided to extend below 
the point of gravity of the head of a sitting occupant. The shaping 
boundary lines of the chambers can easily be produced by a sewing or 
weaving together of the two opposite air bag walls.

DETAILED DESCRIPTION OF THE DRAWINGS 
FIG. 1 illustrates an air bag curtain 2 in a vehicle interior in front of a 
vehicle side window 1, whereby the vehicle side window 1 is covered in the 
event of a crash in the impact area of a vehicle occupant who is protected 
thereby from a hard impact on the vehicle side window 1. 
In a normal driving operation, the air bag curtain 2 takes up a gathered 
storage position along an upper boundary edge of the vehicle side window 1 
in that it is folded in its full width into a receiving channel 3' 
extending along the roof frame 3. In the event of a crash, however, a gas 
generator 4 is activated which is arranged here behind the interior 
paneling of the vehicle in the C-column area and which fills the air bag 
curtain 2 with gas. Thereby, the curtain 2 emerges from its receiving 
channel 3' in the roof frame 3 and spreads out over the vehicle side 
window 1 downward into its effective position. The air bag curtain 2 
remains fastened along its upper, transversely extending edge at the roof 
frame 3, this fastening also comprising two deeper-situated fastening 
points 5, 6 on the A-column and on the C-column. 
By filling the air bag curtain 2 with gas, the air bag curtain 2 is 
tensioned along a tension line 7 illustrated by a dash-dotted line from 
the fastening point 5 on the A-column to the fastening point 6 on the 
C-column. As a result, the air bag curtain 2 is held in its effective 
position A in front of the vehicle side window 1 also in the event of the 
occupant's impact. 
The air bag curtain is manufactured having two opposite air bag walls 8, 
8', which are crossed by gastight boundary lines 9 which form tube-shaped 
chambers 10 which are arranged side-by-side over the width of the air bag 
curtain 2, are spaced from one another and can be filled with gas. These 
individual chambers 10 require a smaller amount of gas for the filling of 
the air bag curtain 2. This is particularly advantageous with respect to 
the side impact because the filling can be achieved in a shorter time span 
and in a more protective manner for the occupant with a lower gas 
pressure. 
After the filling with gas in the event of a crash, the chambers 10 for the 
most part have a circular cross-section 11 and therefore a maximal energy 
absorption capacity when the chambers 10 are loaded by the occupant. The 
circular cross-section 11 is achieved of parallel-extending or mutually 
uniformly approaching or departing boundary lines 9. 
So that the air bag curtain 2 in its effective condition A cannot be 
displaced by the impacting occupant from its position covering the vehicle 
side window 1, the air bag curtain 2 is fixed by one side respectively at 
the fastening point 5 on the A-column and at the fastening point 6 on the 
C-column. As a result of the gas filling, the air bag curtain 2 is also 
tensioned between these two fastening points 5, 6 along the tension line 7 
and is held close to the vehicle side window 1. 
Because of the direction or course of the boundary lines 9, the chambers 10 
are constructed with a larger width than the adjoining areas on this 
tension line 7. This results in a bulging which forms an oval 
cross-section 12 in this area between the fastening points 5, 6 
approximately in the direction of the tension line 7 in each chamber 10. 
Thereby, a larger tension force can be generated between the fastening 
points 5, 6 without impairing the circular cross-sectional shape 11 of the 
adjoining chamber areas. 
An individual construction of the chambers 10 achieves an optimal energy 
absorption in the occupant's impact area as the result of the circular 
cross-sectional shape 11 of each chamber. Nevertheless, a maximal tension 
can be introduced into the air bag curtain 2 along the tension line 7 so 
that the air bag curtain 2 is held securely in its effective position A 
which can be fixed in a particularly secure manner if the tension line 7 
is provided to extend below the gravity center of the head of a sitting 
occupant. The boundary lines 9 of the chambers 10 may be produced in a 
simple manner by sewing or weaving the two air bag walls 8 and 8' 
together. 
The foregoing disclosure has been set forth merely to illustrate the 
invention and is not intended to be limiting. Since modifications of the 
disclosed embodiments incorporating the spirit and substance of the 
invention may occur to persons skilled in the art, the invention should be 
construed to include everything within the scope of the appended claims 
and equivalents thereof.