Mercedes-Benz-Blog TRIVIA:The Research Cars of Mercedes-Benz - PART XVI


Stuttgart, Germany, Nov 19, 2007

Taking its clues from nature – Mercedes-Benz bionic car


* Vehicle: Mercedes-Benz bionic car
* Introduced in: June 2005
* Where: Washington, DaimlerChrysler Innovation Symposium
* Goals: Investigation of the potential of bionics for automotive development, testing of future-oriented diesel engine technology with a novel emission control (SCR technology)
* Powertrain: Turbodiesel engine with common rail direct injection, 2.0 liters displacement, 103 kW (140 hp), emission control using SCR technology, maintenance-free diesel particulate trap

Technical highlights

* Outstanding aerodynamic efficiency (drag coefficient Cd = 0.19) with bodywork modeled on the boxfish
* Light, stable body and body-in-white structure modeled on nature
* Advanced diesel engine with direct injection
* Emission control system using SCR technology and AdBlue reducing nitrogen emissions by up to 80 percent
* Commercial vehicles: production launch in the Mercedes-Benz Actros (2005); passenger cars: production launch in the Mercedes-Benz E 320 BLUETEC (2006, W 211 series) in the USA
* Maintenance-free diesel particulate trap
* Consumption of just 4.3 liters of fuel per 100 kilometers (54.7 mpg) in the European driving cycle
* Infinitely variable AUTOTRONIC automatic transmission - Production launch in the Mercedes-Benz B-Class (2005, T 245 series)
* Door handles which are flush with the outer skin and folded out by electric motors upon being touched
* Front indicators designed as prismatic optical fibers
* High-performance light-emitting diodes as position lights
* Rear light units with high-performance LEDs and prismatic rods
* Cameras instead of rear-view mirrors

With the Mercedes-Benz bionic car – a concept car – the company investigates the great potential of bionics (the combination of biology and technics) for automotive development. It was found that the interplay of future-oriented diesel engine technology and novel emission control yields outstanding results in fuel economy and the reduction in pollutant emissions. For the first time, the engineers specifically looked for a role model in nature, which lends itself to an aerodynamically efficient, safe, comfortable and environmentally compatible automobile not just in detail features but in its overall form and structure. They found this role model in the boxfish.

This fish, which lives in tropical waters, has excellent flow properties despite its angular, cube-like body and therefore has an aerodynamically ideal shape. On a model representing a true-to-the-original copy of the boxfish body, the engineers measured a drag coefficient (Cd) as low as 0.06.

To be able to use this great potential for automotive development, they developed a 1:4-scale car model in a first step, its shape being largely identical with that of the boxfish. On the resulting clay model, a drag coefficient of Cd = 0.095 – an extremely low value in automotive engineering – was measured in tests in the wind tunnel. This corresponds to figures which are achieved with so-called streamlined bodies (Cd = 0.09) and other ideal shapes in terms of aerodynamic efficiency.
The scientists and engineers drew on the findings from these investigations in the development of the bionic car, a fully operational and ready-to-drive compact car with a length of 4.24 meters. It accommodates four people and their luggage, and in terms of safety, comfort and everyday practicality, it incorporates qualities typical of Mercedes-Benz. With a Cd value of 0.19, the concept car ranks among the aerodynamically most efficient automobiles in this category of size.

20 percent reduction in fuel consumption and nitrogen-oxide emissions lowered by up to 80 percent

Alongside maximum aerodynamic efficiency and a lightweight concept gleaned from nature, the advanced turbodiesel engine with common rail direct injection (103 kW/140 hp) and novel SCR (Selective Catalytic Reduction) technology contribute to significant reductions in fuel consumption and pollutant emissions. In the European driving cycle, the concept car consumes 4.3 liters of fuel per 100 kilometers (54.7 mpg) – 20 percent less than a comparable production model. According to the US measuring method (FTP 75), the car does some 70 miles per gallon (combined) – 30 percent more than a production car. At a constant speed of 90 km/h (55 mph), the direct injection engine consumes 2.8 liters of diesel per 100 kilometers, corresponding to 84 miles per gallon in the US test cycle.

With SCR technology and the AdBlue additive, the nitrogen oxide emissions of the advanced direct injection diesel engine can be reduced by up to 80 percent. The aim in testing this engine in the Mercedes-Benz bionic car and und other vehicles is to compensate for disadvantages in fuel consumption by optimizing the combustion processes inside the engine.

AdBlue is an aqueous urea solution which is sprayed into the exhaust system, precisely apportioned to match engine operating conditions. This solution triggers the transformation of nitrogen oxides into harmless nitrogen and water. The reservoir for this additive is accommodated in the spare wheel recess of the concept car; its filling lasts for a distance which corresponds to the maintenance interval of a modern Mercedes-Benz diesel-engined model. In addition, the Mercedes-Benz bionic car study is equipped with a maintenance-free diesel particulate trap.

Bodywork structure: Nature’s construction principle for high rigidity and low weight

In cooperation with bionics experts, the company’s researchers developed a computer-based process for transferring the growth principles in nature to automotive engineering. This process is based on the SKO (Soft Kill Option) method: bodywork or chassis components are dimensioned by means of computer simulation in that the material is made ever thinner and finally cut away completely in low-load areas, whereas highly stressed areas are reinforced. By applying the SKO method to the entire body-in-white structure, weight is reduced by some 30 percent, while the high levels of stability, crashworthiness and driving dynamics remain unchanged. The reduction in weight thus renders an important contribution to a further improvement in fuel economy.

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