Perry Mick wrote:
I finally hooked up a voltmeter to my oxygen sensor. It read between
0.75 and 0.85 when it
was operating (warmed up). Looking on the web, this does not seem to be
a lean condition,
but rather a rich condition. From what I've been able to find, 0.45 is
the optimum, less than
that is lean, higher is rich. Is this correct?
--
Perry Mick
Custom Composite Props
mick@bridgingworlds.com
http://www.ductedfan.com
Hi Perry,
Yes, the standard O2 sensor puts out a voltage between zero (or close to
it ) and 1 volt (lean to rich). 0.75-0.85 is in the power making range.
0.45-0.5 volts is the stoichiometric air:fuel ratio voltage, but not
necessarily the optimum (well. it is for emissions, but not much else) - it
depends. If you want to make power then the air/fuel ratio needs to be
richer than 0.5 If you want leaner mixture, then less than 0.5 volts.
Supposedly 12.65 A/F is Best Power ratio.
Here's some information about lambda (O2) sensors... I found on the web
Lambda sensors come in two basic types, those with heating elements built in
and those without. They all work on some clever principle described by the
Nernst equation, and produce a voltage depending on the gas concentration
gradient across the device. Zirconium Oxide sensors need to be above about
300 C to work, and can be used to measure the Oxygen content in your
exhaust.
In practice you never burn all the available Oxygen, and the amount left
over will be related to the fuel/air mixture present, and the combustion
conditions. Basically, if you're running too weak, more oxygen is present in
the exhaust gas, and if you're running too rich, less oxygen is present.
Nearly all automotive lambda sensors give a 0.5V output for a stoichiometric
air:fuel ratio, and this appears to be 14.7:1.
The curve below may vary slightly from sensor to sensor but is fairly
representative
Ed Anderson
The AirCraft Rotary Engine NewsLetter. Powered by Linux.
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