ETR Control Module with Airbag, Function

The emergency tensioning retractor control module with airbag (N2/2) recognizes the following via two integrated, redundant acceleration sensors.
- Deceleration acting on the vehicle in the longitudinal direction during a front end collision.
- Acceleration acting on the vehicle in the longitudinal direction during a rear end collision.
- Acceleration acting on the vehicle in the lateral direction in the event of a side collision.

In addition the control module recognizes
- the switching states of the (driver and passenger) belt buckle switches
- the momentary status of the passenger seat via the evaluation circuitry for the front passenger seat occupied recognition sensor with automatic child seat recognition (B48).

The control module links all signals received and triggers precisely the airbags/side airbags and emergency tensioning retractors required for optimum protection of the passengers in the event of a collision.

An additional safety sensor is integrated into the control module for protection against erroneous triggering during normal vehicle operation. This sensor, which also functions as a switch, is actuated only by deceleration caused by a front end collision. It is connected into the triggering circuit for the driver and passenger airbags and conducts the full triggering current when they are triggered.

The safety sensor is not connected into the triggering circuits for the driver and passenger emergency tensioning retractors. However, its switching state is checked by the control module before triggering the emergency tensioning retractors. If it has been actuated by the deceleration present, the emergency tensioning retractors are triggered.

In the event of a side collision the safety sensor has no function. Here an additional safety factor against erroneous triggering is achieved by checking the second (redundant) acceleration sensor.