Officially called SPR4 (Snake Pretensioner Retractor), the system comprises a plastic piston instead of conventional metal components to transfer tensioning torque, this meaning in turn that a simpler and lighter weight design has been achieved.
"The pyrotechnical seat belt pretensioner has been an established product for nearly 30 years, but TRW has taken this concept to a new level,” said Harald Lutz, director engineering, TRW seat belt systems.
“Based on our proven production seat belt retractor (ESA 4.0), the SPR4's design is simplified and a new tensioning concept transfers power without limiting functionality."
Aside for being lighter, the new pretensioner can be fitted more easily into any car, thanks to the fact that it is only made up of four main components: the piston, the gas generator, the tube and the pinion.
"Seat belt pretensioners need to generate tensioning torque quickly, accurately and reliably with a stable level of force and the innovative concept allows for this," added Lutz.
The belt pretensioner, part of the passive safety system in a vehicle, acts like an additional system to the belt itself and preemptively tightens the belt to prevent the occupant from jerking forward in a crash. In case of a crash, a pretensioner will tighten the belt almost instantaneously.
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