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Cornering Kingpin
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In addition to local optimisation of the introduction rigidity at the shock absorber strut bracket and at the integral carrier, a cross-functional load path was conceived to further improve the system as a whole. The aluminium struts running in X-direction from the shock absorber strut bracket to the cowl provide support in the event of a crash. Supplemented by a multipiece framework, these struts also help to suppress the Y-movement of the side members. This design allowed the new load path to be incorporated into the limited package installation space in the front section. The forces are applied to the bodyshell structure in the three-piece cowl, which has been configured as a cast aluminium component in the centre section. In this case too, the casting allows a functionally perfect connection with distinct advantages in terms of weight and installation space.
The side members have been designed as combined aluminium extruded sections/castings to optimise crash performance, rigidity and component integration. The protrusions of the extruded aluminium sections of the side members required for package reasons have been designed to also have a positive effect on folding behaviour in the event of a crash. The cavity closed by a foam piece is also used as a resonance volume for the Frontbass system. The side members are connected to the steel passenger cell by means of cast aluminium components that allow a very rigid connection and integration of the integral carrier connection.
Clever combination: sophisticated steel and aluminium joining technology
The firewall area is a sheet steel construction. As well as meeting the functional requirements perfectly, this design also allowed integration of the complex hybrid joint between the aluminium front section and the steel cell. Here one of the major challenges was the mechanical joining technology used for the sophisticated high-strength steels.
In addition to the front section, the integral carriers are also made of aluminium and boast the lowest weight in their class. As well as acting as a component carrier for numerous components, the integral carrier is a central component of the front-end structure when it comes to performing crash and NVH functions.
Compared to the previous model series, the complete cooling module is fastened to the integral carrier in addition to the engine, steering, torsion bar and front axle. The integral carrier's side members also form the third crash load path in the front section. In order to meet these multiple requirements yet still maintain a lightweight design, a complex aluminium mix comprising die castings/permanent mould castings, extruded sections and sheet metal parts was also required here.
The roof is another key area for lightweight design as reducing weight here has a positive effect on the vehicle's centre of gravity and on NVH characteristics. The new S-Class features an aluminium roof – a first at Mercedes-Benz. A major challenge here was integrating the roof into a steel structure. This was achieved by implementing an efficient and simple assembly solution in the bodyshop, which involves the roof being fixed to the bodyshell structure using shackles with defined spacing for the purpose of production in the factory. The resulting gap between the bodyshell structure and the roof ensures that the components are coated completely during the cathodic dip priming process.
One particular lightweight-construction measure involves the use of structural foam pieces in functionally critical node areas to ensure high NVH performance.
Preliminary investigations have shown that comparable performance could only have been achieved by means of solid reinforcements, some of which would have required one-sided joining processes. Such reinforcements would have resulted in a double-figure increase in the bodyshell weight. Due to the way the foam pieces work, it is possible to position them precisely in the functionally critical node areas, since there is no need to take account of production-specific requirements such as joining technology limitations or component joining sequences. Furthermore, it is even possible to achieve frictional connections between cross-sections with several chambers.
Safety first: passenger cell made using high-strength steels
The safety passenger cell consists primarily of steel. Thanks to the use of higher steel grades, the weight has been kept the same as for the predecessor model although far more stringent crash requirements (angled mast) and stricter NVH requirements are met. All relevant components have been increased by one class in terms of material quality, one example being in the area of the B-pillar, roof frame and tunnel reinforcement, where thermoformed ultra-high-strength steels that have been weight-optimised as tailored products with different sheet thicknesses are used. In the lower side member area, an ultra-high-strength steel (CP 1000) is used as a roll-profiled component for the first time. This steel-based lightweight design by material optimisation is also backed by lightweight design by geometrical optimisation, including the formation of a frictional connection between the C-pillar and the rear centrepiece, which allows efficient support of the rear section's side members when the vehicle flexes.
In the case of detachable body parts such as the wings, bonnet and boot lid, the use of aluminium adopted for the previous model series was continued. The aim was to outperform internal and external competitors in terms of weight and to effectively implement the design in production whilst meeting strict requirements in terms of joins and seams. Proof that sophisticated design, lightweight construction and production-friendly product design can actually go hand in hand.
The aluminium hybrid design results in the use of additional mechanical joining technologies. The technical limits of the processes for these joining technologies were determined in collaboration with the supplier, the planning department and production. Consequently it was possible to combine high-strength sheet metal with aluminium for the first time and to reduce the sheet thickness of the components primarily from a functional standpoint. Only thanks to the interaction of lightweight-construction measures and lightweight-construction processes was it possible to make use of the 50 kg lightweight design potential.
Conversely it was then possible to invest in a massive way in performance – in safety, comfort and customer benefit. Result: the bodyshell of the new S-Class is not only lighter, but also clearly tops in performance.
Restraint systems: meticulous design of every detailAlongside the deformation potential of the body and major components, as well as the stability of the passenger cell, it is the quality of the restraint systems that largely determines the risk of injury to the occupants in the event of an accident.
The crash sensors, including appropriate software adaptation to detect the accident type and the collision severity, have been further refined compared to the predecessor model series. New components and features:
• STAR2 electronic control unit
• Pressure sensors for detecting collisions with pedestrians
• Use of sitting position information for adaptive control of the restraint systems
As standard, the driver and front passenger each have a three-point seat belt with triple pyrotechnic retractor tensioning. Retractor tensioning and belt force limiting as well as an electrically reversible inertia reel tensioner are effective via the shoulder belt. The upper belt guide point is anchored to the B-pillar and height-adjustable. The PRE-SAFE® Impulse tensioning system is a world first in the new S-Class (see "Extended PRE-SAFE® protection" section). The rear passengers in the two outer seats have three-point seat belts with inertia-reel tensioner and self-adaptive force limiter, while the centre seat features a standard three-point seat belt system. As optional extras, the seat belt buckle extender, beltbag and cushionbag elevate rear safety to a new level (see Page 70 Extended rear protection" section).
Driver and front passenger airbags: adaptive filling
The driver's airbag (volume approx. 64 litres) is equipped with a two-stage gas generator. Two stages can be activated, depending on the detected vehicle deceleration values, with a delay between triggering of the two stages. In addition to the two-stage gas generator, the front passenger's airbag (volume approx. 112 litres) has a special feature in the form of a pyrotechnically activated adaptive stage. The cushioning of the occupant when plunging into the airbag is made harder or softer depending on the sitting position and gas filling, according to requirements.
The thorax/pelvis sidebags for the driver and front passenger with a volume of 17 litres are integrated in the front seat backrests whilst the rear sidebags with a volume of 12 litres are integrated in the rear side panelling where they are firmly attached to the bodyshell. In the event of a crash, the windowbag cushion (volume approx. 40 litres) is filled by a hybrid gas generator that is located in the roof area behind the B-pillar. The use of a new weaving technology (X-Tether technology) makes the windowbag cushion more stable, meaning that it is easier to ensure effective inflation over a prolonged period of time.
Triggering of the side protection systems is controlled by the Star2 electronic triggering device, which can detect and assess a side collision with the help of a central acceleration sensor, additional satellite sensors in vehicle lateral direction and pressure sensors in the doors. Furthermore, the belt tensioners are triggered together with sidebags and windowbags if a side collision is detected and together with the windowbags if roll-over is detected.
Pedestrian protection: active bonnet and more deformation spaceTo supplement the active safety measures which help to prevent accidents or reduce the severity of accidents, the measures aimed at mitigating the consequences of accidents in the event of collisions with pedestrians have been further developed for the new S-Class. In order to reduce the loads exerted on a pedestrian if their head hits the bonnet of the vehicle, the deformation space between the bonnet and the components beneath it has been optimised. This is achieved in part by appropriate positioning of components such as control units or fluid reservoirs in the engine compartment.
The S-Class also features an active bonnet. In the event of a collision with a pedestrian, sophisticated sensors combined with intelligent algorithms trigger pyrotechnic actuators in the area of the bonnet hinges. These raise the bonnet by around 80 millimetres. The deformation characteristics of the bonnet have been developed specifically to meet these requirements. Further reductions in the impact loads can be achieved by using aluminium and by homogenously reinforcing the inside face of the bonnet. Furthermore, the hardness of the foam in the front bumper has been optimised to reduce the load exerted on the pedestrian's legs in the event of an impact.
Suspension
The world's first suspension system with "eyes"The new S-Class is the world's first car to be able to detect bumps on the road ahead. If the ROAD SURFACE SCAN detects such unevenness by means of the stereo camera, MAGIC BODY CONTROL sets up the suspension in advance to deal with the situation. This innovative suspension system is available as an option for the eight-cylinder models. Standard equipment for the new S-Class includes an enhanced version of the full air suspension system AIRMATIC with continuously adaptive damping control.
The front axle features four-link suspension. Its key characteristics include two individual links (torque strut and spring link) in the lower link plane. The transversely situated forged-aluminium spring link carries the spring strut. The anti-roll bar is connected directly on the steering knuckle, while the forwardsloping torque strut is made of forged aluminium.
A wishbone located high above the lower link plane performs further wheel location functions. This link is also made of forged aluminium, as is the steering knuckle which connects the upper and lower link planes. The fourth link is the track rod which forms part of the rack-and-pinion steering system. The transversely situated steering gear is located in front of the wheel's centre.
The arrangement and design of the wheel location components offer favourable characteristics for the axle kinematics: the kingpin inclination is close to the wheel centre. This provides for large longitudinal force leverage, thus minimising sensitivity to tyre imbalances and fluctuations in braking force. The lower front axle components, the steering gear and the engine mounts are linked with an assembly carrier. This integral carrier, made from high-strength sheet aluminium, is directly bolted to the body.
Due to the unsurpassed wheel location qualities, the S-Class features multi-link rear suspension attached to a subframe. Consistent lightweight construction minimises the weight of the unsprung masses. Four of the five wheel-locating links are made of forged aluminium, as is the hub carrier. The spring link that carries the spring strut is made of single-ply sheet aluminium. In the standard configuration, the rear axle with air suspension features a torsion-bar stabilizer which is directly connected to the rear axle carrier.
The side members have been designed as combined aluminium extruded sections/castings to optimise crash performance, rigidity and component integration. The protrusions of the extruded aluminium sections of the side members required for package reasons have been designed to also have a positive effect on folding behaviour in the event of a crash. The cavity closed by a foam piece is also used as a resonance volume for the Frontbass system. The side members are connected to the steel passenger cell by means of cast aluminium components that allow a very rigid connection and integration of the integral carrier connection.
Clever combination: sophisticated steel and aluminium joining technology
The firewall area is a sheet steel construction. As well as meeting the functional requirements perfectly, this design also allowed integration of the complex hybrid joint between the aluminium front section and the steel cell. Here one of the major challenges was the mechanical joining technology used for the sophisticated high-strength steels.
In addition to the front section, the integral carriers are also made of aluminium and boast the lowest weight in their class. As well as acting as a component carrier for numerous components, the integral carrier is a central component of the front-end structure when it comes to performing crash and NVH functions.
Compared to the previous model series, the complete cooling module is fastened to the integral carrier in addition to the engine, steering, torsion bar and front axle. The integral carrier's side members also form the third crash load path in the front section. In order to meet these multiple requirements yet still maintain a lightweight design, a complex aluminium mix comprising die castings/permanent mould castings, extruded sections and sheet metal parts was also required here.
The roof is another key area for lightweight design as reducing weight here has a positive effect on the vehicle's centre of gravity and on NVH characteristics. The new S-Class features an aluminium roof – a first at Mercedes-Benz. A major challenge here was integrating the roof into a steel structure. This was achieved by implementing an efficient and simple assembly solution in the bodyshop, which involves the roof being fixed to the bodyshell structure using shackles with defined spacing for the purpose of production in the factory. The resulting gap between the bodyshell structure and the roof ensures that the components are coated completely during the cathodic dip priming process.
One particular lightweight-construction measure involves the use of structural foam pieces in functionally critical node areas to ensure high NVH performance.
Preliminary investigations have shown that comparable performance could only have been achieved by means of solid reinforcements, some of which would have required one-sided joining processes. Such reinforcements would have resulted in a double-figure increase in the bodyshell weight. Due to the way the foam pieces work, it is possible to position them precisely in the functionally critical node areas, since there is no need to take account of production-specific requirements such as joining technology limitations or component joining sequences. Furthermore, it is even possible to achieve frictional connections between cross-sections with several chambers.
Safety first: passenger cell made using high-strength steels
The safety passenger cell consists primarily of steel. Thanks to the use of higher steel grades, the weight has been kept the same as for the predecessor model although far more stringent crash requirements (angled mast) and stricter NVH requirements are met. All relevant components have been increased by one class in terms of material quality, one example being in the area of the B-pillar, roof frame and tunnel reinforcement, where thermoformed ultra-high-strength steels that have been weight-optimised as tailored products with different sheet thicknesses are used. In the lower side member area, an ultra-high-strength steel (CP 1000) is used as a roll-profiled component for the first time. This steel-based lightweight design by material optimisation is also backed by lightweight design by geometrical optimisation, including the formation of a frictional connection between the C-pillar and the rear centrepiece, which allows efficient support of the rear section's side members when the vehicle flexes.
In the case of detachable body parts such as the wings, bonnet and boot lid, the use of aluminium adopted for the previous model series was continued. The aim was to outperform internal and external competitors in terms of weight and to effectively implement the design in production whilst meeting strict requirements in terms of joins and seams. Proof that sophisticated design, lightweight construction and production-friendly product design can actually go hand in hand.
The aluminium hybrid design results in the use of additional mechanical joining technologies. The technical limits of the processes for these joining technologies were determined in collaboration with the supplier, the planning department and production. Consequently it was possible to combine high-strength sheet metal with aluminium for the first time and to reduce the sheet thickness of the components primarily from a functional standpoint. Only thanks to the interaction of lightweight-construction measures and lightweight-construction processes was it possible to make use of the 50 kg lightweight design potential.
Conversely it was then possible to invest in a massive way in performance – in safety, comfort and customer benefit. Result: the bodyshell of the new S-Class is not only lighter, but also clearly tops in performance.
Restraint systems: meticulous design of every detailAlongside the deformation potential of the body and major components, as well as the stability of the passenger cell, it is the quality of the restraint systems that largely determines the risk of injury to the occupants in the event of an accident.
The crash sensors, including appropriate software adaptation to detect the accident type and the collision severity, have been further refined compared to the predecessor model series. New components and features:
• STAR2 electronic control unit
• Pressure sensors for detecting collisions with pedestrians
• Use of sitting position information for adaptive control of the restraint systems
As standard, the driver and front passenger each have a three-point seat belt with triple pyrotechnic retractor tensioning. Retractor tensioning and belt force limiting as well as an electrically reversible inertia reel tensioner are effective via the shoulder belt. The upper belt guide point is anchored to the B-pillar and height-adjustable. The PRE-SAFE® Impulse tensioning system is a world first in the new S-Class (see "Extended PRE-SAFE® protection" section). The rear passengers in the two outer seats have three-point seat belts with inertia-reel tensioner and self-adaptive force limiter, while the centre seat features a standard three-point seat belt system. As optional extras, the seat belt buckle extender, beltbag and cushionbag elevate rear safety to a new level (see Page 70 Extended rear protection" section).
Driver and front passenger airbags: adaptive filling
The driver's airbag (volume approx. 64 litres) is equipped with a two-stage gas generator. Two stages can be activated, depending on the detected vehicle deceleration values, with a delay between triggering of the two stages. In addition to the two-stage gas generator, the front passenger's airbag (volume approx. 112 litres) has a special feature in the form of a pyrotechnically activated adaptive stage. The cushioning of the occupant when plunging into the airbag is made harder or softer depending on the sitting position and gas filling, according to requirements.
The thorax/pelvis sidebags for the driver and front passenger with a volume of 17 litres are integrated in the front seat backrests whilst the rear sidebags with a volume of 12 litres are integrated in the rear side panelling where they are firmly attached to the bodyshell. In the event of a crash, the windowbag cushion (volume approx. 40 litres) is filled by a hybrid gas generator that is located in the roof area behind the B-pillar. The use of a new weaving technology (X-Tether technology) makes the windowbag cushion more stable, meaning that it is easier to ensure effective inflation over a prolonged period of time.
Triggering of the side protection systems is controlled by the Star2 electronic triggering device, which can detect and assess a side collision with the help of a central acceleration sensor, additional satellite sensors in vehicle lateral direction and pressure sensors in the doors. Furthermore, the belt tensioners are triggered together with sidebags and windowbags if a side collision is detected and together with the windowbags if roll-over is detected.
Pedestrian protection: active bonnet and more deformation spaceTo supplement the active safety measures which help to prevent accidents or reduce the severity of accidents, the measures aimed at mitigating the consequences of accidents in the event of collisions with pedestrians have been further developed for the new S-Class. In order to reduce the loads exerted on a pedestrian if their head hits the bonnet of the vehicle, the deformation space between the bonnet and the components beneath it has been optimised. This is achieved in part by appropriate positioning of components such as control units or fluid reservoirs in the engine compartment.
The S-Class also features an active bonnet. In the event of a collision with a pedestrian, sophisticated sensors combined with intelligent algorithms trigger pyrotechnic actuators in the area of the bonnet hinges. These raise the bonnet by around 80 millimetres. The deformation characteristics of the bonnet have been developed specifically to meet these requirements. Further reductions in the impact loads can be achieved by using aluminium and by homogenously reinforcing the inside face of the bonnet. Furthermore, the hardness of the foam in the front bumper has been optimised to reduce the load exerted on the pedestrian's legs in the event of an impact.
Suspension
The world's first suspension system with "eyes"The new S-Class is the world's first car to be able to detect bumps on the road ahead. If the ROAD SURFACE SCAN detects such unevenness by means of the stereo camera, MAGIC BODY CONTROL sets up the suspension in advance to deal with the situation. This innovative suspension system is available as an option for the eight-cylinder models. Standard equipment for the new S-Class includes an enhanced version of the full air suspension system AIRMATIC with continuously adaptive damping control.
The front axle features four-link suspension. Its key characteristics include two individual links (torque strut and spring link) in the lower link plane. The transversely situated forged-aluminium spring link carries the spring strut. The anti-roll bar is connected directly on the steering knuckle, while the forwardsloping torque strut is made of forged aluminium.
A wishbone located high above the lower link plane performs further wheel location functions. This link is also made of forged aluminium, as is the steering knuckle which connects the upper and lower link planes. The fourth link is the track rod which forms part of the rack-and-pinion steering system. The transversely situated steering gear is located in front of the wheel's centre.
The arrangement and design of the wheel location components offer favourable characteristics for the axle kinematics: the kingpin inclination is close to the wheel centre. This provides for large longitudinal force leverage, thus minimising sensitivity to tyre imbalances and fluctuations in braking force. The lower front axle components, the steering gear and the engine mounts are linked with an assembly carrier. This integral carrier, made from high-strength sheet aluminium, is directly bolted to the body.
Due to the unsurpassed wheel location qualities, the S-Class features multi-link rear suspension attached to a subframe. Consistent lightweight construction minimises the weight of the unsprung masses. Four of the five wheel-locating links are made of forged aluminium, as is the hub carrier. The spring link that carries the spring strut is made of single-ply sheet aluminium. In the standard configuration, the rear axle with air suspension features a torsion-bar stabilizer which is directly connected to the rear axle carrier.
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No, I'm not. My cars always have keyless go, there is no need for the key to be thick and heavy, I keep it in my pocket.
