Air Bag Control Module: Description and Operation
Air Bag System Description SAS Control Module:
SAS control module
When the crash sensor in the SAS control module detects vehicle deceleration due to the shock of a collision, it outputs an electric signal and simultaneously, the safing sensor detects this and turns ON.
The output control circuit calculates the input electric signal and determines whether or not to send the signal to the I/O (input/output) interface. If the calculated value is more than the value set in the output control circuit, the electric signal is sent to the inflator via the safing sensor.
When the inflator receives the signal from the I/O interface, the inflator generates nitrogen gas to deploy the air bag modules. The bags release the nitrogen gas from a vent hole in the back of the bag to reduce shock to the driver and passenger and to allow easier exit from the vehicle.
Crash sensor
The crash sensor use a piezo electric device to convert distortion (pressure displacement) to an electric signal.
Air bag module
- The air bag module consists of the bag assembly, inflator, bag cover, and base.
- When the air bag module is activated, the inflator generates nitrogen gas. By this gas, the air bag is inflated and pops out from the bag cover, which opens at the tear line.
- The air bag vents the nitrogen gas from the vent hole at the back side of the bag to reduce shock to the driver and passenger.
- The air bag module is replaced as an assembly if it malfunctions or if deployed.
Clock spring connector
- The clock spring connector is part of the combination switch.
- The clock spring connector ensures uninterrupted electrical contact to the air bag module while allowing rotation of the steering wheel.
- The clock spring connector and combination switch are serviced as an assembly.
CAUTION:
- Whenever the steering wheel is removed, before reinstalling it, set the clock spring connector as follows:
1. Set the front wheels straight ahead.
2. Turn the clock spring connector clockwise until it stops. (Do not force it.)
3. Return the connector 2.75 turns.
4. Align the marks on the clock spring connector to the outer housing.
Side air bag module Structure
- The side air bag module is composed of the following parts.
- The bag comes out from the seat back pad and the outside seat back trim breaks during operation.
Activation
1. The igniter is heated by the current that flows from the side air bag sensor to the igniter. This heats the ignition intensifier.
2. The ignition intensifier burns due to its chemical reaction with oxygen, breaks the wall of the compressed gas chamber, and ignites the compressed gas.
3. The compressed gas raises pressure and bursts from the wall out of the breaking outlet.
4. The bag swells from being instantaneously injected with gas and absorbs the collision impact from the driver or passenger.
Side air bag sensor
The side air bag sensor is built into the B-pillar and senses collisions from the side.
Activation
1. When the vehicle is involved in a collision from the side, the safing sensor detects the collision to activate the unit. Simultaneously, the crash sensor within the side air bag sensor detects the deceleration, converts this information into an electric signal, then outputs it.
2. The electric signal output by the crash sensor is calculated at the output control circuit. That calculated value is compared to its own preset value, and if it exceeds that preset value, it operates the side air bag module to deploy.