Seat Belt Tensioner: Description and Operation

INFLATABLE RESTRAINT SEAT BELT PRETENSIONER

The seat belt pretensioners contain a housing, an initiating device, and a canister of gas generating material. The initiator is part of the seat belt pretensioner deployment loop. When the vehicle is involved in a collision of sufficient force, the SDM will cause current to flow through the deployment loops to the initiator. Current passing through the initiator ignites the material in the canister producing a rapid generation of gas and the release of compressed gas, if present. The gas produced from this reaction rapidly shortens the seat belt buckle height.

Each seat belt pretensioner is equipped with a shorting bar located on the connector of the pretensioner. The shorting bar shorts the seat belt pretensioner deployment loop circuitry to prevent unwanted deployment of the pretensioner when it is disconnected.