Operation

The SRS is a safety device which, as a supplement to the seat belt, is designed to protect the driver by operating when the car receives a frontal impact exceeding a certain set limit.

1. Air bag inflator
2. SRS unit
3. Safety circuit
4. Main sensor
5. Airbag

The system is comprised of the airbag assembly (which in turn consists of the SRS unit, airbag inflator, and airbag) and the slip ring.

Operation

As shown in the diagram, the main and safety circuits, and the safety switch are connected in series to the airbag inflator and the battery. A regulator circuit (increasing the reliability of the SRS system by raising the voltage when battery voltage drops) and a back up power circuit are connected in parallel with the battery. The sensors, the safety switch, regulator and back up circuits, and a self – diagnosis circuit are all built into the SRS unit.

Sequence of operation:

1. The main sensor and the safing sensor activate.
2. Power is supplied to the airbag inflator by the battery or the back up power circuit if the battery is disconnected due to the impact.
3. The airbag deploys.

It takes about 0.1 seconds from the beginning of the airbag deployment until it is completely deflated.