Passive safety: Safe with intelligent systems

Mar 9, 2016
True to Mercedes-Benz tradition, the new E-Class sets standards in terms of passive safety, too. For example, the PRE-SAFE® protection concept has now been upgraded into all-round monitoring.
Mercedes-Benz has for years been protecting car occupants with its PRE-SAFE® concept in a host of accident situations. The concept includes various measures to move the occupants into the best possible position prior to an imminent impact. Based on findings from its own accident research, Mercedes-Benz has continuously developed this system further and is now incorporating innovations to upgrade it into an all-round monitoring system. For this purpose, the new E-class is equipped for the first time with the new subsystem PRE-SAFE® Impulse Side. Together with the familiar PRE-SAFE® protection concepts for frontal and rear collisions, it allows a kind of virtual crumple zone that extends all around the vehicle – PRE-SAFE® 360°.
As only a limited crumple zone is available in the case of a side impact, even before the crash, PRE-SAFE® Impulse Side can move the affected driver or front passenger as far as possible away from the acute danger zone as soon as the system detects that a side collision is immediately imminent. For this purpose, air chambers in the side bolsters of the front seat backrest are inflated in fractions of a second. This impulse can move the occupant to the side, away from the acute danger area and towards the centre of the vehicle, thus increasing the distance between occupant and door. At the same time, the impulse is imparted moderately to the occupant, lessening the forces acting on them during the side impact. This can reduce the forces to which the occupant's rib cage is subjected during a side collision.
The system is optionally available for the first row of seats as part of the Driving Assistance package Plus.
PRE-SAFE® Sound - protecting the ears against the noise of a crash
With its new PRE-SAFE® Sound, Mercedes-Benz is for the first time making use of a natural reflex to prepare the occupants' ears for the loud noise normally associated with an accident. The system is based on the fact that the so-called stapedius muscle in our ears reacts to loud noises by contracting in a reflex action. The contraction of this tiny muscle briefly changes the link between the eardrum and the inner ear, providing greater protection against high sound pressures.
Mercedes-Benz uses this natural reflex as biomechanical ear protection for PRE‑SAFE® Sound. This is because an accident can cause noise to which some people have a sensitive reaction. PRE-SAFE® Sound therefore emits a short noise signal through the vehicle's sound system if the risk of a collision is detected. This signal can trigger the stapedius reflex, which prepares the ears for the noise. And thus lessens the risk of hearing discomfort or damage.
Even more intervention scenarios
So far, the PRE-SAFE® system has reacted as soon as it detects an imminent collision or other hazard – such as because of a shock reaction on the part of the driver, e.g. emergency braking or critical steering wheel movements. Or because of unusual vehicle behaviour, such as over/understeer or substantial intervention by assistance systems. For added safety, the system now reacts to even more intervention scenarios. These include a detected fast switch by the driver from accelerator to brake pedal (shock reaction), critical steering wheel movements, now also at low speeds, a clearly autonomous course correction by Crosswind Assist and a detected, immediately imminent side collision.
Beltbag – clever cross between belt and airbag
Three-point seat belts with pyrotechnical belt tensioners and belt force limiters are installed for driver, front passenger and passengers on the outer rear seats. The centre seat of the second row is equipped with a standard 3-point belt system. For the first time, beltbags are optionally available for the outer rear passengers in the E-Class. The beltbag is a combination of seat belt and airbag components - an inflatable seat belt that is capable of widening its belt strap and thus further reducing the risk of injury in the event of an accident. It is used in exactly the same way as a conventional seat belt. In the event of a serious frontal collision, a gas generator on the belt's end fitting inflates the belt strap to over twice its normal width. This enlarges the belt strap area in the upper body region so that the force is distributed more widely than is the case with a conventional belt.
In addition, a host of airbags provides occupant protection in an accident. These include:
  • driver and front passenger airbags
  • kneebag for the driver to protect the knees and stabilise the upper body, which positively influences occupant movement in an accident.
  • a windowbag in the roof area between A, B and C-pillars for the head area of driver, front passenger and passengers in the outer rear seats
  • combined thorax/pelvis sidebags for driver and front passenger, which are able to provide additional protection in the event of a side impact, as well as optionally available sidebags for the outer rear seats
Systematic pedestrian protection
The following measures are implemented for pedestrian protection:
  • Active Brake Assist warns if pedestrians are detected in the danger area by the multi-purpose stereo camera and, if necessary, initiates autonomous braking if the driver fails to react to the warning from the system.
  • Specific flexibility in the frontal region as well as an active bonnet, which can be raised by 80 mm when an impact is detected, thus creating additional deformation space during an impact.
In the event of an accident
After an accident has occurred, various measures dependent on accident type and severity can mitigate the consequences and make fast rescue possible. These include:
  • automatic activation of hazard warning lights
  • emergency shut-off of engine and fuel pump
  • emergency door unlocking
  • emergency call
  • disconnection of the 12 V starter cable
  • high-voltage switch-off
  • emergency switch-off of the air conditioning system
  • emergency interior lighting
  • ventilation by slightly lowering the front windows by a few centimetres
  • exit assistance for the driver by lowering the steering column
Mercedes-Benz emergency call for fastest possible assistance
The E-Class is equipped with Mercedes-Benz emergency call. An emergency call can be made automatically or manually. It is automatically activated as soon as an accident of a certain severity is detected and restraint systems have been triggered. The position data of the vehicle, the chassis number, Mercedes-Benz contact coding, an indicator for automatic or manual triggering, time stamp, language setting of the vehicle and estimated number of occupants are sent to the Mercedes-Benz emergency call centre, which then establishes a voice connection with the vehicle. If there is no response, it immediately alerts the nearest rescue service.
Guidelines for Rescue Services with important information for rescuers
To enable rescuers to work quickly and safely, Mercedes-Benz provides a rescue card for the E-Class in various languages that can be downloaded free of charge. The new E-Class is also equipped with QR code stickers – a small but effective measure with which Mercedes-Benz makes rescuing accident victims faster and safer.
The QR code can be read with smartphones and tablet computers and sends a rescue card for the vehicle model to the display of the rescuers. This card contains all the information needed to rescue casualties quickly.