Freelander - Integrated Safety System
Integrated System
Freelander's twin airbag system is integrated with the revised front seatbelt pre-tensioners, under the control of a single microprocessor.
The pre-tensioners are 'pyrotechnic' - with a special design that allows them to be fired in much the same way as an airbag. This causes the seatbelt to tighten across the body and work in conjunction with the airbags to protect the occupant. The new seat belt load limiters reduce the amount of load on the occupant's chest during deceleration by controlling the webbing payout.
Taking the decision
The Airbag Control Module contains calibrated deceleration sensors, and a safing sensor which discriminates between crash and non-crash events to avoid inadvertent deployment.
If the deceleration sensors register a crash pulse equal to or greater than the predetermined threshold, the combined airbag and pre-tensioner system is deployed.
Less time than the blink of an eye
A signal is sent to the squibs in the airbag and pre-tensioner systems around 18 milliseconds into the impact (depending on crash severity), and these detonate instantaneously, resulting in rapid pre-tensioner activation and airbag deployment. The airbag is fully inflated around 45 milliseconds into the crash (To get this reaction time into perspective, the blink of an eye can take 100 milliseconds).
The airbag then progressively deflates to absorb the deceleration forces of the occupant, and reduce the risk of physical injury from the airbag itself.
The airbag control module measures deceleration pulses only in a forward direction, up to and including 30 degrees either side of the vehicle centre line. any impact outside these parameter will not activate the airbag.
The Benefits
- Integrated system provides better levels of protection.
