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On the Safe Side

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Tags: ZeroAccidents, SeeThinkAct, Safety

In side impact collisions, there may only be a small crumple zone between a passenger and a potential incoming object. ZF has devised a pre-crash-system with airbags that can deploy on the outside of vehicles to help enhance occupant protection.
Achim Neuwirth, July 23, 2019
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Achim Neuwirth has been writing for ZF since 2011. He has specialized in writing texts about all kinds of car-related topics: from vehicles to the technology behind them, to driving and traffic.
In the case of frontal and rear end crashes passengers have a greater amount of crumple zone between them and the object struck by the vehicle. Side crashes can present a greater risk to passengers as there is often little vehicle infrastructure to help lessen crash severity. Almost 700 people die in such accidents every year in Germany, which equates to one-third of all car passengers killed in accidents.

Reducing Passenger Injury Severity by up to 40 Percent

Memmingen, Germany, June 2019. There is a deafening but muted sound, as a vehicle crashes into the side of another medium-sized vehicle without braking. The loud bang that we hear, however, is not caused by the collision, as the impacting vehicle in this demonstration is a soft dummy vehicle. The noise comes from the deployment of a large airbag now visible on the passenger side of the impacted vehicle. If this was a real crash on a normal road, the people in the vehicle likely could have come out of the accident with significantly less severe injuries thanks in part to the external airbag.
“Our pre-crash safety system with an external side airbag has the potential to reduce passenger injury severity in a side impact collision by up to 40 percent“, says Uwe Class, Head of the 'Safe Mobility Systems' Advanced Engineering department at ZF. “Our safety innovation provides an additional crumple zone with which cars have previously not been equipped. A fact that the live crash test has just revealed.“
ZF Proactive Side Impact Protection

A Crumple Zone to Go

In today’s vehicles, conventional front and side airbags in the interior are deployed when the pressure and/or acceleration sensors detect a certain collision. The new pre-crash system, in contrast, makes the decision of whether to deploy the external airbag prior to the collision. This can only happen, however, if the car has a reliable accident prediction system.
A sensor system – i.e. a network of cameras, lidar and radar – therefore tirelessly keep watch for potential threats and dangers. The algorithms employed by the system can determine how each threat is to be assessed – for example, whether a collision is unavoidable and whether the external airbag can and should then be deployed. If the system decides that this is indeed the case, it ignites the inflators to fill the airbag.
“It takes around 150 milliseconds for the pre-crash system to make a decision and take the measures necessary”, explains Class. “This is the blink of an eye prior to the accident that we use to help significantly reduce the risk of injury to passengers.” The pre-crash safety system can reduce the impacting vehicle or object penetrating the car body by up to 30 percent, thereby helping to reduce the injury severity to passengers by up to 40 percent.

The ZF pre-crash-system in action

What is the purpose of a crumple zone?

What is the purpose of a crumple zone?

The external side airbag is the most eye-catching component of the ZF pre-crash-system and is stored in the side sill, waiting to be deployed. Upon deployment, it expands upwards from the side sill, where necessary, and has a volume of 280 to 400 liters, depending on the vehicle model. This provides for an additional crumple zone in the door area between the A-pillar and the C-pillar with an airbag that is five to eight times larger than a typical driver’s airbag.