The F 400 Carving follows the tracks of other vehicle studies, such as the 1996 F200 Imagination and the 1997 F300 Life-Jet, which showcased new steering and chassis concepts. “Drive-by-wire” and “active scroll control” were just two of the central concepts for these automotive research projects. Mercedes-Benz research engineers and scientists refined these ideas and presented them in 2001 at the Tokyo Motor Show at the Mercedes-Benz F400 Carving. The new concept reveals a completely new system that further improves active safety and dynamic handling and provides an even more stimulating driving experience.

20 DEGREES WHEEL CAMBER FOR SAFE AND RELIABLE EFFORT

The epithet "Carving" already suggests the capabilities of chassis technology in this research vehicle. Each time the car enters a curve or bend, two of its wheels tilt inward, riding on a tire tread that has been specially optimized for cornering and has a high friction coefficient for optimal directional stability and road grip. The dynamics are reminiscent of the movements made by alpine skiers using carving skis.

The computer-controlled system on the F 400 Carving varies the camber angle on the outer wheels between 0 and 20 degrees when the car is cornering. The internal wheels and the body of the vehicle remain in their normal positions. ”Active camber control” is the culmination of a research project that spans several years. It all started with computer simulations and bench testing. But now it's time for roadside research. The F 400 Carving is a kind of mobile research laboratory for automotive engineers based in Stuttgart. They intend to use the two-seater open-top to investigate the potential of new chassis systems and to break new ground in chassis technology for the passenger cars of the future. Initial tests and measurements have given extremely encouraging results.

Compared to a modern car chassis, the active curvature control on the Carving F 400 allows up to 30% more lateral stability and 15% more longitudinal forces. The numbers support these claims: while the maximum lateral force on the wheel is usually about 6200 Newtons when the curvature is zero degrees, that number rises to 6900 Newtons when there is a negative curvature of 10 degrees and as high as 7800 Newtons when the A negative curvature is 20 degrees. Thanks to the high level of lateral stability on the outer wheels during cornering, the lateral acceleration on the F 400 Carving is up to 28% higher than on sports cars that rely on conventional chassis technology. When the outer wheels of the Notch F 400 are tilted inwards 20 degrees during curves, the biposto reaches a maximum lateral acceleration of 1.28 g.

This impressive figure is not only an indication of high dynamics in curves and sporting agility, but also signals a substantial improvement in active safety, particularly in emergency situations, such as speeding (excessive) curves or sudden avoidance maneuvers. The research car remains more directionally stable than a car equipped with conventional chassis technology. In addition, it does this for longer and with greater speed.

RUBBER MIXTURE: TIRES TIRE WITH DIFFERENT FRICTION ZONES

The rubber mixture used for the F 400 tires plays an equally important role, as the softer inner tread zones allow for even greater transmission of forces - that is, better grip on the road - when cornering. These “high friction compounds” are generally not suitable for car tires, as the soft rubber mixture is more susceptible to wear than the conventional rubber compounds used. Therefore, the new tire would not normally achieve the mileage that today's tires are capable of.

The camber control active in the F 400 sculpture compensates for this short time: thanks to this innovative technology, the softer interior of the tires only comes into contact with the track when the car is cornering and therefore does not use it so fast. In contrast, the rubber compound that experts have developed for the outside of the tire is much more difficult, having been optimized for longevity, straight-line stability and road roar. In other words, thanks to its asymmetrical contour and special rubber mixture, the newly developed tire provides the answer to an unresolved conflict of objectives: maximum safety in curves and superlative driving dynamics on the one hand; high mileage and excellent stability straight from each other. For the first time, therefore, two different concepts are realized in a single tire, thanks to the active camber control.

HIGHLY PROMISING RESEARCH

Active computer-controlled camber adjustment and asymmetrical tires have brought DaimlerChrysler engineers an important step towards achieving one of their main objectives: to improve already exemplary levels of active safety and driving dynamics for the benefit of future models. But this is just the beginning of what promises to be an extremely fruitful research project: alongside greater lateral acceleration and exemplary cornering stability, this innovative technology offers a number of other benefits on the road:

If there is a risk of skidding due to excessive steering or steering, the system briefly tilts one or more of the wheels in a precisely calculated amount, thus increasing lateral forces and stabilizing the car. This means that active camber control has the potential to increase the effect of ESP®. Together with the electronically controlled steering, which allows for automatic steering correction, this can greatly reduce the risk of skidding.

In the case of emergency braking, all four wheels of the research car tilt at the speed of light, leaving only the inside of the tires - with compound tread friction optimized rubber - in contact with the road. This reduces the stopping distance to 100 km / h by a good five meters.
If there is a risk of aquaplaning, the system is able to optimize the tire contact system in an appropriate amount. A camber of just five degrees is sufficient to achieve the desired effect: a substantial reduction in the risk of aquaplaning. A new generation of sensor systems, currently under development at DaimlerChrysler, detects the water layer on the road surface and sends the measured values ​​to the ECU in the center of the active camber control, allowing the system to automatically adjust the inclination of the wheels to suit to road conditions.

Asymmetric tires would also be beneficial in winter, as the special rubber blend and tread pattern combine to provide extremely high traction, as well as short stopping distances and superlative directional stability. To ensure safe driving on snow or ice, the driver can tilt the wheels at the press of a button, thus allowing the car to work only inside the tires, for better grip on the road.

HYDRAULIC CYLINDERS

Active adjustment of the computer-controlled camber is possible thanks to two-piece hub carriers and a powerful hydraulic system. Each hub support consists of a tilt section and a rigid section: the wheel locating components of a dual-spindle suspension system are attached to the rigid inner sections while the wheel bearings and brake caliper joints are located on the tilting external sections. During bends, piston rods on double hydraulic cylinders press against the inclined sections of the hub holder on the outer wheels, causing them to tilt outwards at the bottom. This way, the wheel can change between 0 and 20 degrees, depending on the road situation. The rear axle driven on the F 400 Carving is designed in the same way as the front axle, with variable length axles being the only big difference.

At the heart of the hydraulic system is an axial piston pump with a working pressure of up to 200 bar. Servovalves on the twin cylinders of the wheels regulate the oil flow to control the degree of retraction and extension of the cylinder. If the driver adopts a dynamic driving style, rapid cylinder movement is required, in which case the pump is assisted by a hydraulic pressure reservoir. A limp-home function is also provided: special shut-off valves interrupt the flow of oil to the hydraulic cylinders and use the pressure available in the system to adjust the camber angle of the wheel to zero degrees.

Steer-by-wire and wire brake

Active camber control, as shown in the F 400 sculpture, represents a major step forward in the development of chassis for future car models. Even in its own right. But the engineers in Stuttgart are taking things a step further, combining this technology with a number of other equally pioneering systems. The key to all of this is drive-by-wire. The F 400 dispenses with mechanical connection components, such as the steering column, with all the axles and articulations that accompany it, and the articulation between the brake pedal and the brake servo. Instead, there are wires that transmit the driver's steering or braking inputs by purely electronic means.

Direction: The electronic steering wheel is equipped with two inductive angle sensors that capture each movement of the steering wheel, convert the measured angle into an electric pulse and transmit the signal to the research car's microcomputers via data line. Computers evaluate these and other current sensor signals, using the data to specify set points for the steering angle of the front axle. In critical situations, the drive-by-wire system can also replace the driver's steering inputs to keep the car safely in balance. Two electric motors, which are directly connected to the rack and pinion direction, move the wheels of the F 400 sculpture. That is why automotive researchers refer to an "electric rack" - a new feature that they developed together with experts towards Mercedes-Benz Lenkungen GmbH. Each electric motor generates half of the steering torque. In the event of a fault, only one of the engines can assume full responsibility for the steering functions. This is, therefore, a redundant system, designed to provide maximum functional reliability. Even the research car's power supply is based on a dual system concept: in addition to a standard 12-volt power supply, the F 400 Carving also has two 42-volt systems that are used primarily for electronic steering.

Brakes: Brake-by-wire is already a reality at Mercedes-Benz. The Sensotronic Brake Control (SBC) high pressure brake operates according to the following principle. When the brake pedal is pressed, an electrical signal is produced, which is routed to a microcomputer. A sophisticated sensor system ensures that the microcomputer receives a continuous feed of data on the driving dynamics of the car. The electronic system can therefore calculate and modulate the brake pressure for each wheel, according to the situation in question. The end result is significantly improved braking safety when cornering.
Together with the Sensotronic Brake Control, the F 400 sculpture braking system contains yet another technical highlight that really sets it apart: the brake discs (330 mm in diameter) are made of carbon fiber reinforced ceramic, a high-tech material . able to withstand extreme temperatures between 1400 and 1600 degrees Celsius. It is also about a third lighter than cast iron.

XENON LIGHT OF FIBER OPTICS

Equally new is the F 400 Carving headlight system. For the first time, DaimlerChrysler is using state-of-the-art fiber optic technology to transmit the light produced by xenon lamps. These optical fiber bundles, made up of thousands of individual fiberglass wires, allow for the physical separation of the light source and headlights - an advantage that mainly benefits the sports car design, as the headlights take up only a short distance. amount of space. This, therefore, allows for an extremely flat and low front.

The main and middle beam light is generated in two cylindrical housings below the engine hood. Each contains a xenon lamp and the light emitted by these lamps is concentrated by elliptical reflectors. The focal points of the reflector reflect the light in the fiber optic lines, which, in turn, guarantee the lossless transmission of light to the headlights. Special lens systems in the headlights diffuse the light to illuminate the road. In addition, the F 400 Carving has two side lights for curves. These fixed position halogen lamps light up when a certain steering angle is reached. They can also be activated by a button, for use as fog lights. A space-saving design is also the hallmark of the indicators: powerful LEDs generate light that is then dispersed through prismatic lenses.

VEHICLE BODY: LIGHT CARBON FIBER

The open two-seater body is made of carbon fiber reinforced plastic (CFRP). Already tried and tested in the world of Formula 1 car racing, its main properties are minimum weight and maximum strength. It weighs about 60% less than steel, making the research car body 100 kilos lighter. DaimlerChrysler engineers use a clever mix of three materials for the F 400 Carving chassis: steel, aluminum and carbon fiber (CFRP).



EXTERIOR: THE LANGUAGE OF DYNAMICS

Whatever the way you look, from any angle, the speedster's body is like that of a perfectly proportioned and superbly conditioned athlete. The profile is structured by wing-shaped sections that stretched powerfully on the wheels, harmoniously drawing them in the general concept of the body, but without restricting its freedom of movement. Small wing sections forwards and backwards from the wheels reinforce this effect, making the wheels the dominant focus of attention when viewed from the side.

The design team also skillfully used the distinctive wing sections to give the F 400 Carving a distinctive feature, making the headlights an integral part of the wings and using the light caps to form two “eyes”, while definitely increasing the seductive allure of the sports car. This stylistic detail is possible thanks to the lighting systems that incorporate state-of-the-art fiber optic technology, since conventional headlights are simply too big to be incorporated in the limited space available in the wing sections.

And, of course, the two-seater face would not be complete without the three-pointed star, centrally positioned in the renowned Mercedes sports tradition. It forms the focal point of another important design feature that extends centrally across the engine hood, evoking images of the unmistakable arrow-shaped nose of the McLaren-Mercedes team's Silver Arrows. This particular detail is on its way to becoming a classic sports feature of Mercedes-Benz, having already graced the studies of the Vision SLR and Vision SLA sports car.

Arguably the most striking feature of all, because they are so steeped in tradition, gullwing doors have come to symbolize the Mercedes-Benz brand. It is now exactly 50 years since the first Mercedes-Benz Gullwing created a sensation, marking the beginning of the SL legend. The F 400 designers took this feature and reinterpreted it in the spirit of contemporary design and technology, proving that the idea is as stylish and stimulating as it was so many years ago. The gullwing doors of the research car are not attached to the ceiling as they were in the original 300 SL. Instead, they rotate upwards 60 degrees thanks to special gaskets, supported by gas springs.

The muscular contour of the door leads to a sweeping and powerful profile that forms a prominent line that extends to the end of the sprinter's tail, where it functions as a fender for the rear wheels. The tail part of this section houses the rear lights, just as its counterpart at the front incorporates the headlights. The thin prism lenses allow the indicators, taillights and brake lights to blend effortlessly with the overall design concept and, in addition, shed extremely impressive light on things.

INTERIOR: HIGH TECHNOLOGY

A look inside the cockpit reveals another great design theme for the F 400 Carving: technology in its purest form. Technology that focuses on the essentials, on what was originally motorsport and, therefore, on everything that is absolutely central to this idea. Nothing more, nothing less.

Of course, this initially smells like purism, a totally stripped-down driving machine. But a closer look quickly reveals everything: the perfect finish, the best materials and a passion for detail. The designers at Mercedes' studios - in Como, northern Italy and Sindelfingen, southern Germany - dedicated themselves to the task at hand, giving the interior a characteristic appearance based on classic aspects of bodystyling and design. Nowhere is this more apparent than in the “wing” theme, the instrument panel being a perfect case: there is no firm visual link between the panel and the central tunnel. It seems to be “floating” in space like a majestic wing and thus it looks extremely light and almost delicate.

The idea of ​​technology in its purest form is most clearly exemplified by the transmission tunnel, which has the shape, color and texture of a cast aluminum transmission bell. As such, it echoes the racing car cockpits of the 1920s and 1930s, a time when drivers had to settle for pure metal and little else. The simple slider controls for the blower and heater, the metallic lever for the SEQUENTRONIC transmission and the oval ventilation outlet above the transmission tunnel reinforce these images of times gone by, but behind each of these classic-style features is the state -of-art. art technology.

Passengers of the F 400 sculpture are awaited by carbon seats where they immediately feel in tune with this evocative car and its technology: man and machine in perfect harmony. The seats provide superlative side support and can be individually adjusted, despite their one-piece design. The multi-layered fiber texture means that it is possible to vary the backrest inclination without the need for joints or hinges - just a small lever mechanism. Together with the spring and damper systems under the seat, the multi-piece upholstery ensures effective vibrational damping for good seat comfort.