Frontal Restraint Devices

The frontal Supplemental Inflatable Restraint (SIR) system supplements the protection offered by the driver and front passenger seat belts. The frontal SIR system deploys an air bag from the center of the steering wheel and from the right side of the instrument panel (Figure 1).

A frontal crash of sufficient force up to 30 degrees off the longitudinal centerline of the vehicle will deploy the frontal air bags (Figure 2). The knee bolsters absorb crash energy. The driver and passenger knee bolsters are below the instrument panel. The steering column is collapsible.

FRONTAL SIR SYSTEM DESCRIPTION
The frontal SIR system consists of the following components:
^ An Inflatable Restraint Sensing and Diagnostic Module (SDM)
^ An Inflatable Restraint Steering Wheel Module
^ An Inflatable Restraint Steering Wheel Module Coil
^ An Inflatable Restraint I/P Module
^ An AIR BAG Warning Lamp in the Instrument Panel Cluster (IPC)

The inflatable restraint Sensing and Diagnostic Module (SDM), Inflatable restraint steering wheel module coil, inflatable restraint steering wheel module, inflatable restraint I/P module, and the connecting wires make up the frontal deployment loops. The function of the frontal deployment loops is to supply current through the frontal inflator modules, which will cause deployment of the frontal air bags. Deployment occurs when the SDM detects vehicle velocity changes severe enough to warrant deployment.

The inflatable restraint Sensing and Diagnostic Module (SDM) contains a sensing device (Accelerometer) that converts vehicle velocity changes to an electrical signal. The SDM compares this electrical signal to a value stored in memory. When the generated signal exceeds the stored value, the SDM performs additional signal processing and compares the generated signals to values stored in memory. When two of the generated signals exceed the stored values, the SDM will cause current to flow through the frontal inflator modules, deploying the frontal air bags.