SRS System Description - Seat Belt Tensioner
ELR Seat Belt Tensioner With Load Limiter
The ELR seat belt tensioner with load limiter is composed of a gas generator, a ring gear, a pinion, an ELR locker, and a spool. When the seat belt tensioner operates, it quickly tightens the seat belt and improves the occupant's initial restraining effect (preventing the occupant's body from moving forward). When the load exceeds the preset value, the load limiter keeps the restraining effect while sending out the seat belt to protect the chest of the passenger.

Operation of Seat Belt Tensioner
1.
The gas pressure in the gas generator circulates the ball in the pipe, and presses it against the ring gear. This connects the ring gear to the pinion.

2.
When the ball reaches the ring gear, it presses the ring gear against the pinion so the gear turns with the pinion. The spool that is connected to the pinion winds the seat belt.
Operation of Load Limiter
3.
If the seat belt is rapidly pulled out, like an occupant sliding forward during a collision, the seat belt operates the lock mechanism, engaging the pawl to the frame gear. That locks the locking base and its integrated torsion bar and spool.

4.
When a certain amount of load is added to the seat belt when the locking base is locked, the torsion bar is twisted, and the spool is rotated, allowing the seat belt to be pulled out.

5.
When the seat belt is pulled out, the ring gear pushes back the ball, and the ring gear is released from the pinion.