>please visit the following webpage to find Your "fantasy"
>already working ;-))
>http://www.zeropollution.com/zeropollution/index.html
This site has some interesting information and some pics of cars of
futuristic design. It describes Guy Negre as inventing the EV3 engine, and
patenting it.=20
http://www.zeropollution.com/zeropollution/default_zero_emissions.html
This page has a pic of a large engine similar in general outline to a
diesel engine. The text says it is "a radically new internal combustion
engine". (The diagram even shows a combustion chamber.) The claim to fame
of this engine is its very low exhaust pollution. It runs on petrol, LPG or
diesel - compressed air is not mentioned. The funny looking taxi vehicles
on the front pages supposedly have these engines fitted.
The same site also has a page describing a compressed air motor, with a pic
showing a different motor (actually it looks like a compressor to me) and
says "the car of the future works on compressed air".
http://www.zeropollution.com/zeropollution/default_no_fuel.html
There are a few details of how it might operate - such as "A jet of cold
air is delivered at high pressure into the combustion (?) chamber which is
already charged up with hot air. This provides enough force to run the
vehicle." This engine can supposedly also run on petrol when it needs to go
over 50 mph.=20
I'm wasn't sure if these two engines are the same or different. But then I
found the following article in a very respected international weekly
magazine and things became clear, finally, (luckily a friend of mine has a
subscription and I can download old articles)
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The Economist. Oct 26, 1996
Car engines - Not all hot air=20
THERE is something silly about the four-stroke petrol engine.
Although it is the workhorse of almost all passenger vehicles it
suffers from some glaring inefficiencies. Only one of the four
strokes of the piston provides power to thecar while during
part of another stroke the piston is moving against the pressure
of the ignited fuel. All of this is an extravagant waste of energy.=20
Such compromises are necessary because of an oddity in the
engine's design-namely that the initial compression of the
combustible gas its ignition by the spark plug and the
power-producing expansion that follows all occur in one and
the same place at the top of the same cylinder. Over the years
alternative designs have been proposed that ease this
constraint. Guy Negre an engineer in Brignoles in France
whose background is in Formula One engine designthinks he
has hit on a particularly ingenious variant which can run far
more efficiently and cleanly than a four-stroke engine on the
same amount of petrol. As a bonus and without any
modification the engine can also be made to run on nothing
more than compressed air.=20
At the heart of Mr Negre's engine is a small combustion
chamber. A piston in a compression cylinder outside this
chamber forces air through a valve into it compressing and thus
heating a mixture of air and petrol in the process. With all
valves to the chamber closed the hot mixture is ignited. The
design of the engine allows the fuel to burn over a period up to
four times longer than in a four-stroke engine. The longer burn
time means that the fuel is consumed far more completely
leading to less in the way of unwanted by-products such as
carbon monoxide and nitrogen oxides.=20
In the final part of the cycle the hot gas escapes through a valve
into a separate expansion cylinder where it drives a piston
cooling in the process. Oneof the benefits of having separate
compression and expansion cylinders is that the expansion
cylinder can be made several times larger than the compression
cylinder. This takes maximum advantage of the stroke that
provides the engine's power. Another benefit is that at the end
of this expansion the gas is at atmospheric pressure and a
temperature of only 100 degrees C. The output of
conventionalengines by contrast is usually at a pressure of
several atmospheres and a temperature of 500 degrees C
which means that lots of potentially useful energy is
beingthrown away and demands a complicated exhaust system
to cool and depressurise the gases. As a result of these
advantages Mr Negre's engine is some 50% more efficient than
the four-stroke variety.=20
The benefits of the design do not stop there. Because the
expansion piston provides power at every second stroke rather
than every fourth Mr Negre's engineprovides the increased
mechanical efficiency of the two-stroke engines common
onmotorcycles. Yet unlike such engines it pollutes much less
and is a great deal quieter because the explosion of the fuel
happens in the small combustion chamber rather than being
allowed to propagate through the cylinder as in conventional
motors. The design also allows the engine to be light: fully
functioning test versions weigh only 34kg (75lb).=20
But the most surprising aspect of Mr Negre's invention is that it
does not necessarily need petrol at all. He has found that
forcing a burst of cold compressed air into the combustion
chamber can deliver sufficient power to the piston to drive a
car. While engines running on compressed air are nothing new
the novelty in this case is that cold compressed air at 40
atmospheres of pressure is being added to that chamber when
it has already been charged up withair by the compression
stroke. Since compressing air also heats it the air in the
chamber is at about 400 degrees C and 21 atmospheres of
pressure. A hot gas expanding can provide a lot more useful
mechanical energy than the same quantityof cold gas at the
same pressure. Although less powerful than a petrol model
thezero-emission version of Mr Negre's engine can power a
car in city traffic for one hour on 15 litres of compressed air.=20
This clean engine does however require a source of
compressed air. One way to do this would be to have an
electrically driven compressor on board. In other words to
make the car an electric one in disguise. But rather than having
to wait ages for batteries to recharge a pressure refill at the
local petrol station would take only a minute. And with the
savings made by having a smaller lighter engine and no exhaust
a car could easily accommodate a compressor that could run
off the energy produced by braking. In contrast to an ordinary
electrically powered car though this one could easily be
switched while driving from compressed-air injection to fuel
injection giving it the necessary power tozip along a motorway.=20
The first commercial prototype of Mr Negre's engine
unmemorably named the MDI-Ev3 is currently being tested by
ADMP a small engineering outfit that he hasset up for use in cars
and buses. With the backing of MDI an engine developer
inLuxembourg ADMP hopes to sell a licence for its technology
to a big engine-manufacturer. Public transport should provide a
convenient test-market for the engine and MDI has already
begun discussions with the Parisian transportauthority RATP as
well as with private bus firms to equip urban buses with the
compressed-air engine. A Parisian bus could run an entire day
on 1500 litres of compressed air which could be stored on
board. If Mr Negre's brainchild takes off Parisian smog may
one day be reduced to the fumes of Gauloises.=20
=A9 1996 The Economist Newspaper Limited. All rights reserved=20
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This article has some really good info in it. My only area of suspicion is
that the author is in the second last paragraph, where he says the energy
from braking can be used to power the compressor, appears to be describing
an over unity situation. Maybe he means the energy from braking can be used
to sometimes power the compressor.=20
Whatever, it does appear to be a workable engine. It just remains to be
seen if it can be developed to measure up to real life demands.
bye all.
Ted