New Bag-in-Roof makes Headlines

The roof-mounted airbag (technically, Bag-in-Roof or BiR) celebrated its premiere back in 2014. In 2020 the application of the third BiR generation was launched. Regarded as a pioneer of this innovative, passenger-protecting restraint system, ZF is one of the few suppliers on the market. “Our roof-mounted passenger airbag can be a totally valid alternative to traditional dashboard-mounted airbags. It gives designers a lot of valuable extra freedom” explains Alfonso Bustos, Group Leader in ZF Spain Airbag Engineering.

This animation demonstrates how the airbag deploys from top to bottom of the windshield in front of the passenger. This enhances passenger safety through the advanced restraint system.

The airbag system is providing optimized packaging at reduced weight. It is available as a single-stage airbag with a volume up to 160 liters, or as a 190-liter dual-stage version. Compared to the first-generation airbag, ZF engineers have managed to improve both packaging and weight. They have also managed to fit into the same space a single- or dual-stage gas inflator, gas diffusion channel and airbag with enhanced vehicle assembly features.
So there does need to be some space available in the headliner, which is why it is not surprising that the first production vehicle to feature the innovative airbag was an SUV with suitably generous headroom: the Citroën C4 Cactus. The Bag-in-Roof was subsequently used in other PSA Group vehicles, such as the Citroën Berlingo, Peugeot Rifter and Opel Combo.

Modern car users are calling out for more screens. In general, experts believe that future motorists will attach much higher value to a car’s interior, making it a key purchase criterion. “With our Bag-in-Roof, designers can make their dashboards as deep, spacious, narrow, functional – or even digital – as they like,” emphasizes Bustos.

But that’s not all. The airbag module also reduces loads and stresses on the windshield. This interaction between airbag and windshield could generate stress on the glass under certain circumstances. Whereas, the roof-mounted airbag deploys in parallel with the windshield, reducing the risk of stress to the glass.

In short, the Bag-in-Roof offers many advantages. But why should front-seat passengers be the only ones to benefit? “We currently work on developing roof-mounted airbags for front passengers, and we believe that in the future, roof-mounted airbags could also be used to protect rear-seat passengers,” explains Bustos. For rear-seat passengers, the airbag would unfold along the back of the front seats. In the future, new cockpit and steering-wheel designs could see the Bag-in-Roof helping to protect drivers as well.