The principles of Integral Safety, in particular accident safety, apply regardless of the platform. Like all other Mercedes, the EQS therefore features a rigid passenger compartment, special deformation zones and state-of-the-art restraint systems. PRE-SAFE® is standard.
The fact that the EQS is based on an all-electric architecture also opened up new design possibilities for its safety concept. Thus, the installation space for the battery could be favourably selected in a crash-protected area in the underbody (for details on battery safety, see separate chapter). And because there is no large crankcase on board, the behaviour in a frontal crash could be modelled even better. In addition to the standard crash tests, the car's performance in various additional load situations was verified and extensive component tests carried out at the Vehicle Safety Technology Centre (TFS). Internally the new body structure bears the designation "flat-floor concept".
Safety structure: designed for many eventualities
The body of the EQS is made for the most part from aluminium. In addition to the outer skin, the longitudinal members are also made from this material. Additional reinforcement elements made from high-strength steel are also used in the main floor. In the bodyshell structure, press-hardened steel reinforcements are intelligently integrated and combined with high-strength, hot-formed steel components. This is how the strict Mercedes crash requirements are met.
So that the front end of the EQS absorbs energy as evenly as possible, a large-scale crossmember links the two longitudinal members together. As in every Mercedes-Benz, the cross connection not only serves as self-protection, but is also a key component for the protection of other road users. Deformable crash boxes are attached to the crossmembers, which helps to increase ease of repair in the event of minor damage.
In a severe frontal impact, two aluminium longitudinal members made from extruded profiles absorb the main energy. A supporting role is played by an upper load path on the shock-absorber strut and a lower load path along the integral carrier. The integral carrier made of steel not only accommodates the eATS and axle components, but it also plays a key role in the event of a crash. In the case of severe deformations, the wheels form an additional load path, whereby they move towards the rear and are braced against the sill and/or side wall. The geometry and strength of the sills have been designed for this accordingly. The battery is protected between the integral carrier and the battery housing by honeycomb-shaped elements. The battery housing itself is extremely rigid and allows for relatively little deformation, so that the cells inside are not damaged. Reinforcing structural components have been additionally integrated into the front area of the underbody with minimal overlap for the load conditions.
In principle, in a side impact only a very small deformation path is available. Extremely sturdy structures in the EQS therefore serve to protect the occupants as well as the battery. Alongside the doors with their reinforcements, the side wall structure also comprises the pillars, the side roof frame and the side members/sills. Cross reinforcements in the underbody as well as the very rigid battery housing contribute to the high stability in a side impact. The extruded aluminium support profiles of the sills are shaped specifically and designed in terms of their deformation characteristics in such a way as to enable damage to the battery modules to be avoided as far as possible.
The EQS is also equipped for a rear impact. As with the front-end assembly, a crossmember with bolted-on crash boxes helps to distribute the impact energy from a one-sided load to both longitudinal members. Thanks to the specific design of the structural components and the rear axle carrier, the requirements in terms of battery safety have been fulfilled.
In a rollover it is particularly important that sufficient headroom is retained. At Mercedes-Benz, global requirements in terms of survival space are applied, which are checked by means of the roof-drop test for example. These naturally apply to the EQS as well.
High-voltage system: automatic shut-off in accidents
The battery, high-voltage (HV) cables and other HV components have been designed and protected in such a way that they meet Mercedes-Benz's high safety requirements in the event of an accident. You can read more about this in the chapter "Under the magnifying glass: high-voltage safety".
The multi-stage protection concept of the high-voltage (HV) system has already proven itself in the other Mercedes-EQ models. In case of danger, it can be automatically switched off and disconnected from the battery. A distinction is made between a reversible and an irreversible shut-off. The reversible shut-off occurs in more minor accidents. In this case it is possible to switch the high-voltage system back on again when an insulation measurement carried out by the vehicle beforehand does not detect an error. This means that vehicles still capable of being driven can continue their journey. Only in severe accidents, in which as a rule the vehicle is in any case no longer capable of being driven, is the high-voltage system irreversibly switched off. It can no longer be activated without repair. When shutting down, there is a provision to ensure that within a few seconds there is no residual voltage in the high-voltage system outside the battery that could cause injury.
There are also shut-down points where emergency teams can deactivate the high-voltage system manually. Furthermore, as standard the EQS features crash monitoring when stationary.
Acoustic Vehicle Alert System: special sound as a warning for pedestrians
The electric car-specific innovations include an Acoustic Vehicle Alert System (standard). This makes it easier for pedestrians to notice the EQS at low speeds. One sound generator sits weatherproof in the front right wheel arch and in the rear underbody respectively. An EQ-specific sound is generated up to a vehicle speed of approx. 30 km/h. Initially it becomes louder and higher with increasing speed. This change allows conclusions to be drawn about the driving status (braking/acceleration).
Above 20 km/h the sound is then already gradually reduced, since the vehicle can then be perceived by its tyre and wind noise. If the speed drops from a higher speed back down to 30 km/h, the sound is faded in again. When reversing, an intuitively recognisable interval tone sounds regardless of the speed.
Modern restraint systems: from B for belt airbag to W for window airbag
In addition to driver and front passenger airbags, a knee airbag on the driver's side is also standard. It protects the legs from contact with the steering column or instrument panel in a severe frontal crash. This can prevent or lessen the severity of injuries.
The standard window airbags can reduce the risk of head impact with the side window or penetrating objects. In the event of a serious side collision, the window airbag on the side of the impact extends from the A- to the C-pillar like a curtain over the front and rear side windows. If a rollover is detected, the window airbags can be activated on both sides.
Vehicles for Europe also have a centre airbag to meet new rating requirements. During a severe side impact, it positions itself between the driver and front passenger seat, reducing the risk of their heads making contact. It is integrated into the driver's seat backrest in the middle of the vehicle.
In conjunction with power rear seats, the EQS is equipped with side airbags in the rear. They protect the chest area on the outer rear seats in the event of a severe side impact and supplement the protection provided by the standard window airbags.
The belt airbags (optional extra) ensure that passengers in the outer rear seats are particularly well protected in the event of a severe frontal collision. The inflatable webbing widens its contact area in the chest and shoulder area almost threefold when triggered. This can reduce the loads acting on the occupants' thorax.
In conjunction with the Exclusive nappa leather Package, the EQS has designer belt buckles at the front and rear. They support buckling up, because the lights of the belt buckle pulsate at that time. When stationary and at low speed, the lights are solid.
The EQS has i-Size child seat attachments as standard on the two outer rear seats. With two anchors each between the seat back and the seat cushion, corresponding child seats are installed particularly quickly and securely. Top tether attachment points behind the rear head restraints provide additional support.
PRE-SAFE®: precautionary protection as standard
The PRE-SAFE® preventive occupant protection system is fitted as standard in the EQS. Together with the familiar precautionary measures in the event of a potential frontal and rear-end crash, PRE-SAFE® Impulse Side (available in conjunction with the Driving Assistance Package Plus or the Driving Assistance Package with DRIVE PILOT) forms a kind of virtual crumple zone that extends around the vehicle.
As only a limited crumple zone is available in a side impact, PRE-SAFE® Impulse Side (availability depending on selected equipment) can move the affected driver or front passenger away from the danger even before the crash 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.