General System Description

Description:

The Supplemental Inflatable Restraint (SIR) system helps supplement the protection offered by the driver and front passenger seat belts by deploying an air bag from the center of the steering wheel and from the top of the right side of the instrument panel.

The air bag deploys when the vehicle is involved in a frontal crash of sufficient force up to 30 degrees off the centerline of the vehicle. To further absorb the crash energy there is a knee bolster located beneath the instrument panel for both the driver and passenger and the steering column is collapsible.

SYSTEM DESCRIPTION

The SIR system consists of the Sensing and Diagnostic Module (SDM), the driver inflator module, the SIR coil assembly, the passenger inflator module and the "AIR BAG" warning lamp in the instrument cluster. The SDM, SIR coil assembly (driver side only), driver inflator module, passenger inflator module and connector wires make up the deployment loops. The function of the deployment loops is to supply current through the inflator modules, which will cause deployment of the air bags in the event of a frontal crash of sufficient force, up to 30 degrees off the centerline of the vehicle. The inflator modules are only supplied enough current to deploy when the SDM detects vehicle velocity changes severe enough to warrant deployment.

The SDM contains a sensing device which converts vehicle velocity changes to an electrical signal. The electrical signal generated is processed by the SDM and then compared to a value stored in memory. When the generated signal exceeds the stored value, additional signal processing is performed and the generated signals are compared to signals stored in memory. When two of the generated signals exceed the stored values, the SDM will cause current to flow through the inflator modules deploying the air bags.