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.

The seat belt pretensioners remove slack from the driver and passenger front seat belts during a frontal impact. The frontal SIR system deploys the seat belt pretensioners with the frontal air bags.

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

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:

1. An Inflatable Restraint Sensing and Diagnostic and Seat Belt Pretensioner Module (SDM)
2. An Inflatable Restraint Steering Wheel Module
3. An Inflatable Restraint Steering Wheel Module Coil
4. An Inflatable Restraint I/P Module
5. A Driver Seat Belt Side Buckle Pretensioner
6. A front Passenger Seat Belt Pretensioner
7. An AIR BAG Warning Lamp in the Instrument Panel Cluster (IPC)

The inflatable restraint Sensing and Diagnostic and Seat Belt Pretensioner Module (SDM), inflatable restraint steering wheel module coil, inflatable restraint steering wheel module, inflatable restraint I/P module, driver seat belt pretensioner, front passenger seat belt pretensioner, 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 and the pretensioners, deploying the seat belt pretensioners, in the event of a mild frontal collision, and deploying the frontal inflator modules and the pretensioners in the event of a mild-to-severe frontal collision. Deployment occurs when the SDM detects vehicle velocity changes severe enough to warrant deployment. The seat belt pretensioners fire first, removing any slack in the driver and front passenger shoulder belts.

The 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 generates 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 and the pretensioners, deploying the frontal inflator modules and the pretensioners.