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DaimlerChrysler is using a new concept
vehicle to examine the great potential of bionics for
automobile development, and has achieved outstanding
results for fuel consumption and emissions with a combination
of pioneering diesel engine technology and innovative
emission control methods.
The Mercedes-Benz bionic car study will have its world
premiere at this year's DaimlerChrysler Innovation Symposium
in Washington. To realise the Mercedes-Benz bionic car,
the engineers at the Mercedes-Benz Technology Centre
and the DaimlerChrysler Research department have for
the first time looked for a specific example in nature
which not only approximates to the idea of an aerodynamic,
safe, comfortable and environmentally compatible car
in terms of details, but as a formal and structural
whole.
The example arrived at was the boxfish. Despite its
boxy, cube-shaped body, this tropical fish is in fact
outstandingly streamlined and therefore represents an
aerodynamic ideal. With an accurately constructed model
of the boxfish the engineers in Stuttgart were able
to achieve a wind drag coefficient of just 0.06 in the
wind tunnel.
In order to use this great potential for automobile
development purposes, specialists at DaimlerChrysler
first created a 1:4 car model whose shape was substantially
based on the boxfish. During tests in the wind tunnel,
a drag coefficient of 0.095 - a previously unprecedented
value in automotive engineering - was measured for this
clay model.
It corresponds to the values achieved with highly streamlined
shapes (Cd 0.09) and other aerodynamically ideal forms.
DaimlerChrysler utilised the findings from this research
during the development of the Mercedes-Benz bionic car,
a fully functioning and roadworthy compact car with
a length of 4.24 metres and space for four occupants
plus luggage.
With a Cd value of just 0.19, this concept vehicle is
among the most aerodynamically efficient in this size
category. 20 percent lower fuel consumption and up to
80 percent lower nitrogen oxide emissions In addition
to superb aerodynamics and a lightweight construction
concept derived from nature, the 103 kW/140-hp diesel
engine and innovative SCR technology (Selective Catalytic
Reduction) greatly contribute to fuel economy and a
further reduction in exhaust emissions. In the EU driving
cycle the concept car has a fuel consumption of 4.3
liters per 100 kilometers - 20 less than a comparable
series-production car.
In accordance with the US measuring method (FTP 75)
the range is around 70 miles per US gallon (combined),
which is about 30 percent more than for a standard-production
car. At a constant speed of 90 km/h the direct-injection
diesel unit consumes only 2.8 liters per 100 kilometers-
corresponding to a range of 84 miles per gallon in the
US test cycle.
DaimlerChrysler is currently testing its SCR technology
worldwide. By this means, and with the additional operating
fluid "AdBlue", the nitrogen oxide emissions of the
direct-injection diesel engine can be reduced by up
to 80 percent. The aim of these trials is to avoid
the fuel consumption disadvantages by optimising the
in-engine combustion processes.
This is where Mercedes-Benz car engineers are benefiting
from the experience gained by their colleagues in the
commercial vehicle sector, where SCR technology is
already in successful use. DaimlerChrysler also intends
to use the great potential of this process for diesel
passenger cars in future, and will initially be offering
SCR technology in the USA when the trials have been
completed. "AdBlue"
is an aqueous urea solution which is sprayed into the
exhaust system in precisely metered quantities, depending
on the engine operating status.
This converts the nitrogen oxides into harmless nitrogen
and water. The reservoir for this service fluid is
located in the spare wheel recess of the concept car,
and its capacity is sufficient for a mileage corresponding
to the service interval for a current Mercedes diesel
model. The Mercedes-Benz bionic car study is also equipped
with a maintenance-free diesel particulate filter.
Great rigidity and low weight - a growth principle
designed by natures "Boxfish", the aerodynamic
model for the concept car, is also a prime example
of rigidity and light weight. Its skin consists of
numerous hexagonal, bony plates which provide maximum
strength with minimal weight and effectively protect
the animal from injury.
DaimlerChrysler researchers examined this bionic structure
and transferred this principle to the Mercedes-Benz
bionic car study with the help of a special calculation
process. The process is based on the principles of bone
formation and for instance allows up to 40 percent more
rigidity to be achieved in the external door paneling
than would be possible with conventional designs.
If the entire bodyshell is calculated according to this
bionic principle, the total weight is reduced by around
one third with undiminished strength and crash safety. |
