irishcar.com - Renault's latest safety research

In a continuation of the safety research emphasis that gave the company the first ever 5-star rating in the Euro NCAP crash testing programme, for 2002 and 2003 Renault is actively pursuing other innovations in the domain of passive safety. New technology is being developed for the passenger restraint systems, such as an anti-slide airbag in the front and a frontal airbag for the rear seats.

The many passive safety innovations offered as part of the Renault System for Restraint and Protection, the second and third generation SRP, have positioned the company’s models at class-leading level.

Double pretensioners introduced on safety belts, as part of the Renault third generation SRP, have proved particularly successful in holding occupants firmly in their seats at the moment of impact. It is not, however, adaptable to all types of vehicles. On three-door saloons, the presence of a second pretensioner built onto the outboard side of the front seats would impede access to the rear of the vehicle.

As an alternative to the double pretensioner, Renault has developed an anti-sliding airbag for the two front seats. In the event of impact, the unit, housed within the seat cushion, deploys in two phases:

The gas generator inflates the metallic envelope which compresses the foam of the cushion and holds the occupant against the structure of the front seat before he or she has even begun to move.

The shape formed by the metallic envelope deforms to assume the shape of the occupant’s pelvis, while the pressure within is held constant during the impact thanks to a deflation controller situated beneath the module. The anti-sliding airbag thus positions the occupant securely relative to the safety belt, and reduces the level of risk to the abdomen and lumbar regions, and thus the danger of serious injury.

At the same time, repeating the principle of the load limiter protecting the thorax by limiting the load exerted on it by the safety belt in the event of impact, Renault is also working on the development of front seat safety belts equipped with a second load limiter (rated at 600daN 1) for the lap-strap section of the belt. This is intended to provide even more effective protection of the pelvis by avoiding, for example, fractures of the iliac wing type.

Meanwhile, since the idea was first presented in 1999 as an exploratory exercise in R&D, Renault has actively pursued the development of a back seat frontal airbag, with a volume of 60 litres and incorporated within the safety belt. This will allow the load exerted by the back seat safety belts to be reduced and will provide still further improved head, neck and thorax protection for the back seat passengers.

This new airbag will also result in the prevention both of childrens’ heads hitting their knees, and of adults’ heads hitting the backs of the front seats. The company expects such a system to be ready for market introduction towards 2003.

Renault’s special concern has been that all the elements of adult protection systems are developed according to particularly strict design, and that part of this requirement is that the various systems (airbags, safety belts etc.) should present no danger for children.

Introduced in Laguna II in 2001, the safety belts with pretensioners and load limiters in the rear side seats also play an important role in this area. During an impact, the pretensioner tightens the belt across the child or its seat, avoiding the risk of folding movement which often results in serious head injury in the forward-facing position (impact of the head against the backrest of the front seat). At the same time the load limiter allows the load exerted on the thorax of a child aged over 4 years, sitting in a booster seat, to be reduced.

In addition to the Easyfix child seat introduced in 2000, Renault now offers two new seats meeting the Isofix standard: the Elios shell-cradle for new-born infants and the Duo seat for children aged from 6 months to 4 years.

The Isofix system comprises two anchoring rings situated at the junction of cushion and backrest for the safer attachment of a child seat to the vehicle. Renault engineers have added a third attachment point, connecting the backrest of the child seat to the vehicle and thus avoiding any risk of it folding forward in the event of impact. Specialists are agreed in saying that the widespread adoption of the Isofix system would result in a 22% reduction in the number of serious injuries (especially to the neck) suffered by children in the age range of 0-4 years.

Renault was the first manufacturer to introduce safety belt load limiters in 1995 in Mégane, as part of its first-generation SRP. At the end of 1997, the second-generation SRP 2 in Mégane combined new controlled-deflation frontal airbags with load limiters which allowed the thorax load to be reduced to only 400daN compared with the usual 900daN. These new frontal airbags served not only to prevent the head from striking the steering wheel or the dashboard, but now also played an active role in terms of absorbing the energy of deceleration during the impact.

In 2001, Renault took a further step forward in the area of occupant restraint by developing for Laguna II its innovative third-generation SRP.

This system, with no equivalent in the market, combines variable-volume frontal airbags (two levels of inflation) with safety belts already equipped with 400daN load limiters. The two levels of inflation are differentiated according to the intensity and violence of the impact. The challenge is to progress beyond the second-generation SRP, already a source of significant improvement in the area of accidentology, by ensuring even better protection in the event of very severe impacts, without at the same time creating secondary effects in impacts of lesser intensity.

At the same time, as part of this new system, the Renault approach differed from others through its use of two pretensioners for the driver rather than the usual one. By holding the occupant more firmly against the seat, the double pretensioner arrangement significantly reduces forward movement of the driver during impact and considerably improves protection of the lower limbs (with a strong reduction in the risk of knee injuries), while also reducing abdominal injury by greatly reducing the risk of submarining.

Remember that submarining occurs when the occupant slides forward beneath the lap-strap section of the safety belt, shifting the pressure of the latter onto more fragile areas of the body such as the abdomen, thus sometimes leading to serious or even fatal injuries in the event of impact.

However, in addition to the double pretensioner, the anti-submarining feature has been strengthened in all seats. The seat cushion support structures with their special bulges and parts of the safety belt have been improved. The back seat passengers are now provided with three 3-point safety belts, the side seats being equipped with safety belts featuring pretensioners and load limiters calibrated at 600daN .

Finally, to protect the occupants during side impacts, the third-generation SRP includes side thorax airbags housed within the front seat backrests as well as curtain airbags for head protection, housed in the cantrails and serving both the front and back seats.

Renault has 600 employees working on safety and spends 100 million euros annually to R&D in safety systems. Some 400 crash tests are carried out every year, along with 4,000 virtual crashes.