ZF Lifetec has announced that it is bringing its new electromechanical e.Locking seatbelt system to series production. It is available in the ACR8.S seatbelt retractor unit and electrifies the sensor and triggering system, offering significantly more design freedom for auto makers as well as comfort for the occupants. It will also be available as an option for ACR8 and SPR6 generations.
ZF Lifetec has developed this solution in anticipation of the future when autonomous driving functions are more widespread, with new seating concepts and positions becoming more attractive, such as passengers adopting a resting position. These positions will require the seatbelt to be integrated into the seat, which is made much easier by the new e.Locking system from ZF.
With conventional systems, one mechanical sensor responds to the acceleration of the belt spool movement while the other mechanism detects the acceleration of the entire vehicle. Typically, a ball sensor is used and in the event of a sudden acceleration or deceleration of the vehicle, this can ultimately block the belt spool and prevent the belt from being pulled out.
“The steel ball sensor in particular requires the retractor to be mounted outside the seat, ideally in the vehicle’s B-pillar,” explained Harald Lutz, senior vice president, global engineering, ZF Lifetec.
However, this design makes it difficult to integrate the belt into the seat. “To ensure that occupants in these positions are optimally protected by a seatbelt system, an integrated belt system is required. We have now made this much easier with our e.Locking function,” said Lutz.
The new e.Locking system in the seat-integrated ACR8.S belt retractor replaces the 12mm to 13mm steel ball previously used with an electromagnetic coil that locks the retractor electromechanically via a signal from a central ECU. The vehicle’s acceleration, deceleration and tilt are measured centrally by sensors in an ECU, evaluated by an algorithm, and a signal is then sent to the coil when the belt retractor should be mechanically locked.
The e.Locking system also offers various other advantages. For instance, the system can also be synchronized with driving programs so that, for example, a locked seatbelt provides more support during dynamic cornering. The system can also increase occupant comfort, for example by enabling the belt to extend unhindered on bumpy roads, where today a ball sensor would repeatedly lock briefly.
The e.Locking system from ZF is located directly on the retractor, in the same place as the previous mechanical system; the locking mechanism via a pawl remains unchanged. The release algorithm and the control unit will also be part of the ZF Lifetec portfolio.
