Automotive Engineering - January/February 2021 - 24

RIDING ON AIR:
Activated carbon aims at autos
and a sense of stability for AV occupants. Employing the technology to
help reduce AV occupants' potential
motion sickness could be another
course of development.
Air-suspended seats already are commonly used in trucks, buses and off-high-

way vehicles, but in many cases there is
very little space under the driver's seat;
packaging improvements enabled by
activated carbon would be welcomed by
designers. Coakley injects another potential vehicle application: " Mountain bikes
are also an exciting opportunity for us, "

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MATERIALS FEATURE

he said. " Air is preferred [as a spring] because it is light; suspension actuation is
long, performance expectations are high! "
As for carbon activation for acoustics,
Coakley sees two potential areas of interest. First, Carbon Air has identified what it
terms " high-grade activated carbons "
and discovered how to impregnate them
into open cell foams in a way that the
binder does not mask their pores. The
result is a range of materials said by the
company to have " extraordinary noiseabsorption characteristics. " At the lowest
frequencies, the materials can outperform
the best conventional acoustic foams of
more than twice the thickness, saving
weight and space, the company claims.
" This creates opportunities throughout
the vehicle, particularly for the newer
generation of coupes and sports SUVs
that have high floors and low roofs, and
where every millimeter of trim saving can
be critical, " Coakley said. As active noise
control gains favor, " the more that can be
achieved passively, the better the performance of the active system, " he added.
The second application is for loudspeaker enhancement, particularly
around larger sub-woofer installations.
" One luxury car maker explained to us
that their top-of-the-range audio systems
occupy almost a third of trunk space due
to use of an enlarged sub-woofer.
Activated carbon, properly specified, can
reduce the space required for that by up
to a half, " noted Coakley. He believes
there is an opportunity for fusion of the
two applications. In-vehicle audio is carefully tuned to match the acoustic behavior of the cabin interior and Carbon Air's
modeling and materials capabilities are
claimed to allow it to improve both the
sound of the speakers and the environment in which the system operates.
" We can halve the size and significantly
reduce the weight of the loudspeaker,
without a loss in bass performance. Our
materials can be half the thickness of the
best acoustic foams, " Coakley asserted.
" In pneumatics, there are limits on which
cavities you can occupy (activated carbon
is largely uncompressible), and the benefit changes according to the pressure.
Roughly speaking, for each half liter of
activated carbon added to an air spring, it
behaves as if it is nearly one liter larger. "
AUTOMOTIVE ENGINEERING

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Automotive Engineering - January/February 2021

Table of Contents for the Digital Edition of Automotive Engineering - January/February 2021