26-05-2012, 01:21 PM
Compressed air car
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The history of compressed air vehicles
One cannot accurately claim that
compressed air as an energy
and locomotion vector is recent
technology. At the end of the 19th century,
the first approximations to what
could one day become a compressed
air driven vehicle already existed, with
the arrival of the first pneumatic locomotives.
In fact, two centuries before
that Dennis Papin apparently came up
with the idea of using compressed air
(Royal Society London, 1687). In 1872
the Mekarski air engine was used for
street transit, consisting of a singlestage
engine. It represented an extremely
important advance in terms of
pneumatic engines, due to its forward
thinking use of thermodynamics, which
ensured that the air was heated, by
passing it through tanks of boiling water,
which also increased its range between
fill-ups.
Compressed air engine
This engine was developed between
the end of 2001 and the beginning of
2002. It uses an innovative system to
control the movement of the 2nd generation
pistons and one single crankshaft.
The pistons work in two stages -
one motor stage and one intermediate
stage of compression/expansion. The
engine has 4 two-stage pistons, i.e. 8
compression and/or expansion chambers.
They have two functions: to compress
ambient air and refill the storage
tanks; and to make successive expansions
(reheating air with ambient thermal
energy) thereby approaching isothermal
expansion. Figure 3 shows the
compressed air engine.
Compressed air technology
After twelve years of research and development,
Guy Negre has developed
an engine that could become one of
the biggest technological advances of
this century. A French engineer by profession,
he has designed a low consumption
and low pollution engine for
urban motoring that runs on compressed
air technology (Figure 2). The CATS
(Compressed Air Technology System)
“air car” from Motor Development International
is a significant step for zeroemission
transport, delivering a compressed
air-driven vehicle that is safe,
quiet, has a top speed of 110 km/h and
a range of 200 km.
Distribution and valves
To ensure smooth running and to optimize
energy efficiency, air engines use
a simple electromagnetic distribution
system, which controls the flow of air
into the engine. This system runs on
very little energy and alters neither the
valve phase nor its rise.
Articulated con-rod
The MDI con-rod system allows the piston
to be held at Top Dead Centre for
70o of the cycle.This way, enough time
is given to create the pressure in the
cylinder. The torque is also better, so
the force exerted on the crankshaft is
less substantial. Figure 4 shows the articulated
connecting rod and the drive
train.