Em 4/4/2011 09:37, Olin Lathrop escreveu:
> Matt Rhys-Roberts wrote:
>> Could anyone recommend a primer on designing plasma ignition, i.e.
>> very high energy spark ignition systems? My idea is to seriously
>> improve the tired old ignition system on a 2-cylinder 4-stroke
>> motorcycle, and I'd
>> like to experimentally create the fiercest spark that's reasonably
>> possible.
> Then maybe you can explain why that matters.  Obviously you need a spark =
in
> that kind of engine to start combustion.  I've heard people talk of stron=
ger
> sparks being better, but nobody has ever explained exactly why.  What is =
the
> advantage of a stronger spark past reliably starting combustion?  Once so=
me
> combustion starts, why can't it be considered the "spark" for further
> combustion until it runs to completion?  No matter how strong the spark,
> wouldn't it still only ignite a small portion of the mixture in the
> cylinder, which means it's relying on the combustion chain reaction for m=
ost
> of the burning regardless of how strong the spark is?


With a stronger spark you start by igniting a larger mass of mixture and
it takes less time for the whole mass inside the combustion chamber to burn=
..

This may not be important at low RPM, but at higher RPM, the faster the
combustion the most efficiency you get.
If the ignition takes too long, the pressure is not at the maximum when
it would be more effective, that is, in the first 90 degrees of the
down-stroke.


Isaac

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