Air bag system for side collision protection

Apparatus for protecting vehicle occupants during side collision are disclosed, including at least one air bag mounted in a vehicle seat and a sensor for pyrotechnically initiating inflation of the air bag. The sensor is mounted on a frame connected to the vehicle body and on which the vehicle seat is mounted, and the vehicle body's sides and/or doors include compression load transfer plates for the direct transmission of energy to the sensor for bag inflation upon deformation of the corresponding side and/or door of the vehicle body.

FIELD OF THE INVENTION 
The present invention relates to an arrangement for protecting vehicle 
occupants during side collisions, comprising at least one air bag mounted 
in a vehicle seat and a sensor for initiating pyrotechnic means for 
inflation of the bag. 
BACKGROUND OF THE INVENTION 
An automobile normally protects the passengers best during collisions from 
the front or the rear since the deformation paths and/or crumple zones are 
relatively long. It is therefore important that passenger protection 
during side collisions should be improved, such improvement occurring for 
example by the use of air or other gas-filled cushions which are more 
generally termed "air bags". 
There are many known air bag systems designed to offer protection during 
side collisions, but none of these however offers a satisfactory solution 
to the problem of providing a adequately effective side collision 
protection system. 
For instance, there are systems having the air bag placed in the door and 
which cooperate with an electronic sensor system. But these systems suffer 
from the disadvantage that it is difficult to achieve correct adjustment 
and adequate protection against damage. Furthermore a diagnosis system is 
required for regular control of the electrical system and the air bag has 
to be relatively large in order to cover all the possible adjustment 
positions of the vehicle seat, i.e with respect to the adjustability in 
the longitudinal and height directions and with respect to the back rest's 
inclination. 
The document GB-A-2 255 535 shows a further arrangement whereby an air bag 
is placed in the door and connected with a pyrotechnic sensor system. This 
system is simpler since no electrical system is required, but otherwise 
presents the same disadvantages as in the aforementioned system which 
means that the door panel will be complicated and the compartment is more 
limited as regard the inclusion of strengthening members, beams etc. 
GB-A-2 232 936 discloses an air bag in the vehicle seat with a sensor 
located in the door. The advantage with this system is that the bag is 
always located in the correct position with respect to the passenger, but 
the disadvantage is however that the signal transmission from the door to 
the adjustable seat is complicated and vulnerable. 
SUMMARY OF THE INVENTION 
An object of the present invention is therefore to achieve an effective and 
reliable air bag system for side collision protection. 
This object is achieved according to the invention in that the sensor is 
mounted on a frame in the vehicle seat and connected to the vehicle body, 
and in that the sides and/or doors of the vehicle comprise compression 
load transfer means which extend to the respective sensor in such a way 
that the sensor can be triggered by a deformation of the corresponding 
side and/or door of the body. 
Further advantageous embodiments of the invention will become apparent from 
the following description and figures of an exemplary embodiment.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
The vehicle seat shown in FIG. 1 comprises a back rest 10 which is 
adjustably connected to the seat cushion 11. The seat cushion 11 is 
provided with a strengthening inner frame 12 which is dimensioned to 
withstand side forces and which is mounted on a lower frame 13 allowing, 
in a manner known per se, the adjustability of the seat in the vehicle's 
lengthwise (longitudinal) direction and allowing possibly also the 
adjustability of the seat height. A tube with a gas generator 14 arranged 
at each end thereof is placed in the outer side of the back rest 10 and 
cooperates with an inflatable air bag 15 (or other gas-inflatable cushion 
or bag) which is shown in an inflated condition in FIG. 1 and 2. The 
non-inflated bag 15 is normally packed into the seat in a position 
adjacent to the gas generator and behind an openable seam in the 
upholstery fabric. Both ends of the gas generator 14 are connected with a 
pyrotechnic sensor 16 via NONEL Pyrotechnic lines 17 which are internally 
"powdered" with highly explosive material. On actuation of the sensor 16, 
a pyrotechnic flame propagates through the line 17 with a speed of about 
2,000 m/sec. When this flame reaches the gas generator 14, the bag 15 will 
be inflated in a few ten-thousandths of a second. 
FIG. 2 shows the seat 10, 11 with lower frame 13 and the frame 12 which 
takes up side forces and which comprises two lateral tubes 12a. These 
extend through a connection piece 12c and project outwardly from the outer 
side of the seat like two impact bumpers (impact fenders) with a front and 
a back end piece 18 and 19 respectively. These two side impact bumpers are 
contained within a panel 20 which in the lateral direction closes tightly 
against the end pieces 18 and 19. The front end piece 18 is always located 
in the area of the side door irrespective of the seat's adjustment, said 
side door being a structural part which is more easily deformable than the 
door pillar positioned close by. 
FIGS. 3 to 6 show two variations of the end pieces 18 in end view and side 
view. In the embodiment according to FIGS. 3 and 4, the sensor 16 is 
placed inside the end of the tube 12a. The sensor's abutment stud 16a 
projects outwardly a small distance from the end of the tube and can be 
operated by end piece 18 which is pivotally connected with the end of the 
tube via an S-formed portion 18a. 
In the embodiment of FIG. 5 and 6 the sensor 16 is placed above the end 12a 
of the tube. The sensor's abutment stud 16a projects somewhat above the 
end of the tube and can be operated by an end piece 18 which, as in the 
foregoing embodiment, is pivotally connected with the end of the tube via 
an S-formed part 18a. Due to the fact that the arrangement of the end 
piece 18 is such that it has a significant extension in a plane extending 
crosswise and, to a greater extent, perpendicular with respect to the 
sensor's abutment stud 16a, a widened field of operation is obtained. 
FIG. 7 shows a schematic view of one example of how the vehicle's door 21 
can be formed in order to transfer the deformation forces from a vehicle 
22 coming in from the side, through the door via a cellular plastic block 
23 to the end piece 18 and the sensors 16 mounted in the seat's stable 
tube frame 12. 
The collision force from the colliding vehicle is lead quickly through the 
door via the stiff cellular plastic block 23 and the door panel to the 
sensor in the seat frame. The door can alternatively be equipped with an 
inner plate or sheet structure 24 as shown in FIG. 8. The plate structure 
comprises longitudinal and lateral plates 24a and 24b respectively in the 
door interior, said plates bridging the space between the strengthening 
member 25 in the door and a door panel 26 mounted on the inside of the 
door (with respect to the vehicle). The panel 26 presents similarly an 
inner structure which transmits the deformation forces in turn to the 
sensor 16 in the seat panel 20. FIG. 8 shows the seat panel 20 and the 
sensor 16 in solid lines in its lowest position of adjustment and with 
dashed lines in its highest position of adjustment. 
The extent of coverage provided by the compression load transferring means 
23 and 24 in the door 21 must be sufficiently large in order to at least 
cover the sensor over the whole range of adjustment of the seat. 
The sensor 16 reacts only when two conditions are fulfilled, namely that 
the abutment force has to exceed a certain value (e.g. 500N) and that the 
process must occur with a certain speed (e.g. 3 m/sec). 
The transfer of the ignition pulse from the sensor to the gas generator can 
occur via one or several pyrotechnic lines (or tubes), depending on the 
design of the gas generator. 
An extra air bag can also be used, above the one shown, in order to protect 
the passenger's head. An example of such an air bag has been indicated in 
FIG. 2 in dashed lines. This air bag 15a is activated by the same sensor 
16 and can be inflated by the upper of the two gas generators 14. 
The risk of accidental actuation is extraordinarily low since the door has 
to be deformed substantially before the sensor is affected. Thus, for 
example, someone kicking the vehicle door would not actuate the sensor. 
The invention is not limited to the above described embodiments, but can be 
varied considerably within the scope defined by the following claims.