Electric vehicles by Daimler feature safety concepts which meet the highest standards – a tradition that lives on.
Doubts about safety are one of the recurrent prejudices regarding electro mobility. According to sceptics, electric vehicles could easily catch fire in case of an accident. Another fear: emergency services personnel could risk fatal electric shocks when operating on damaged electric vehicles. For decades, Daimler has been a pioneer in the field of vehicle safety. The collapsible steering column, the crumple zone and the robust passenger cell are just a few of the developments which are attributed to the former head of pre-development and doyen of passive safety, Bela Barényi (1907-1997). Markus Hermle, Head of the department for Passive Safety in electric vehicles explains how developers at Daimler are currently working on bringing electric vehicles up to the same safety standards as combustion engine models.
Mr. Hermle, how does the safety architecture of electric vehicles differ from that of conventionally powered models?
Markus Hermle: Before I go into the differences, I would like to first speak about what they have in common. Mercedes-Benz has been leading in the field of vehicle safety for decades. We intend to continue to making this a core feature of the brand in the age of electro mobility. In short, our aims here have not changed. There are of course several differences with regard to e-mobility, but the basic mechanical principles for the crumple zone, the robust passenger cell and restraint systems are still true for electric models. The battery as a source of energy is a new element to consider; together with the new drivetrain, it is revolutionising the overall vehicle concept. Not only are the design and dimensions of the vehicle changing; the complete components package in it is as well.
Mercedes-Benz has been leading in the field of vehicle safety for decades. We intend to continue to making this a core feature of the brand in the age of electro mobility.
Which details are of particular importance here?
Hermle: Thanks to the new drive concept, the tunnel in the vehicle interior is no longer required. Structurally this is something completely new; with the combustion engine being replaced by a smaller electric motor, completely different vehicle architectures and design solutions have become possible. We have gained a great deal of freedom regarding the design of the vehicle which in turn can be used to achieve the best possible safety solutions. These freedoms are particularly apparent with a platform that is being designed specifically for battery-electric vehicles.
Compared to conventional engines, electric drive systems require considerably less space, which means that the front section of the vehicle is now much shorter than before. How does this affect the crumple zone?
Hermle: Due to the new structures, we must absorb greater forces at a very early stage and disperse them in a deliberate manner. At the same time, we must also prevent intrusions and ensure an equally robust passenger cell under these new conditions. Avoiding deformations in the foot area, for instance, remains just as important with an electric architecture. In short, the fundamental principles remain the same, only the framework under which we are operating has changed. The focus is always on the protection of vehicle occupants.
The focus is always on the protection of vehicle occupants.
Many of the parts contributing to the safety architecture of conventionally powered vehicles are missing in electric vehicles. What difference does this make?
Hermle: We will interpret safety regarding electro mobility in particular Mercedes manner. In assembling an optimal package with the new components, we aim to develop the best possible safety concept for the crumple zone and the robust passenger cell. Conceptually speaking, we are in uncharted territory.
Moving forwards, it seems that electro mobility is giving way to a completely new interior concept with a lounge-like character. How can passive safety be adjusted accordingly?
Hermle: As autonomous driving develops further too, we may expect new degrees of freedom, i.e. if the vehicle interior is remodelled. To this end, we are working on innovative safety concepts which take into account that in the future occupants will no longer sit in pre-defined seats as they do today.
The fear that batteries could catch fire after an accident is widespread. What is the ideal location for an energy storage unit?
Hermle: The battery is definitely safety-relevant. The best location for it depends on its size. With hybrid vehicles the batteries are so compact that they can be positioned in a protected position above the rear axle, for example. With a battery-electric vehicle, the batteries are considerably larger – the greater range being one of the reasons. Thus, the only sensible place for them is underneath the passenger cell. However, the development of batteries continues with leaps and bounds so that new solutions for the installation space are evolving which in turn affect the vehicle concepts in the various segments.
How do you protect the battery in order to eliminate the risk of fires?
Hermle: We are particularly cautious in this regard. With the hybrid models, the batteries are located in a protected position above the rear axle. With large batteries located beneath the passenger cell, we focus on side impacts above all. We're developing concepts to minimise the potential damage in these areas in case of an accident. With regard to high-voltage safety, we are also working on protective structures to avoid endangering emergency service personnel, for example.
At the crash centre, we are extremely well-prepared for the special requirements of electro mobility.
Daimler has just brought a state-of-the-art crash centre into service. How important is this centre to your work?
Hermle: When the centre was being designed, we considered all the new scenarios. For the alternative drive systems, we took all the possible risks into account that could occur when testing these models in an early prototype stage. In addition to appropriately trained and experienced personnel, special technical equipment is a great help here. At the crash centre, we are extremely well-prepared for the special requirements of electro mobility.
With conventional vehicles, engineers can fall back on a wealth of experience – not with electro mobility. How does this deficit affect development?
Hermle: We have decades of experience in calculating crashes. But with the new electric models everything is changing. The initial development stages of electric vehicles also take place digitally – from the structural design to occupant protection measures. However, as we are dealing with completely new concepts and effect mechanisms, ensuring that the hardware is not damaged, i.e. by means of crash tests, is a very important additional process when monitoring the digital development process. But we also benefit from the experiences we gained by working on electric and fuel cell prototypes in the past.
Bela Barényi was one of the fathers of passive safety. Are his patents still of importance today?
Hermle: The fundamental principles he defined have not changed, in spite of the circumstances being completely different today. Barényi's patents, such as the crumple zone and the robust passenger cell, remain just as relevant with electric vehicles.
In the world's most modern crash centre, Daimler carries out around 1,000 crash tests every year. The centre offers, amongst other things, the possibility to test side impacts, collisions between two cars, trucks and electric models. Furthermore, developers can simulate rollovers and collisions at crossroads. The centre also offers testing facilities for trucks, passenger cars and buses, as well as a 200 metre crash-test lane. Daimler invested 200 million euros to build the new technology centre which spans some 55,000 square metres.