Vent Valve
Airbags with pyrotechnically activated vent valve are used for the first time in a BMW vehicle on the F01/F02.
This measure serves to adapt the hardness of the airbag in possible accident scenarios with small persons or persons sitting close to the steering wheel.
On the basis of the crash severity, belt status and seat position information, the crash safety module decides whether the vent valve is activated or not.
The vent valve is an exhaust vent incorporated into the airbag, which is closed by an arrester band. The arrester band ends in a cylinder, in which there is a blade. In the event of triggering, the blade is pushed in the cylinder by the pyrotechnical actuator and the arrester band is cut through.
Due to the airbag inner pressure, the exhaust vent opens outwards and the hardness of the airbag is controlled by the gas venting.
| Index | Explanation |
|---|---|
| A | Vent valve is closed by arrester band |
| B | Squib triggered, blade is deployed |
| C | Blade cuts through retaining strap and vent valve opens |
| 1 | Retaining strap |
| 2 | Housing |
| 3 | Cylinder |
| 4 | Piston with blade |
| 5 | Squib |
| 6 | Squib connection |
The active vent valve is normally activated for smaller, lighter occupants.
If the system, (due to the seat position) detects a heavy occupant, a reduction of the airbag pressure is not desirable.
In this case, the active vent valve remains closed and is activated at a later stage for disposal firing, when the occupant is no longer in contact with the airbag.
Vent valve remains closed
Vent valve is opened