O2 sensor response times

[Garfield Willis]

On Tue, 28 Mar 2000 13:42:04 -0800, "Fritz Moore" <fbmoore at ucdavis.edu>
wrote:

>	Can the wide range 02 sensor measure AFR on the rich side of
>stoichiometric?
>
>	If so is this because it adds 02 to the sample and then measures the 02
>current required to get back to a lean i.e. 02 present condition?
>
>	I guess my real question is how can it measure AFR by 02 content if there
>is no 02 content in rich conditions?

Yes, right there is *depletion* of O2 under rich conditions; hence, the
O2 pump in these sensors must *supply* O2 ions to bring the sample
chamber back to stoich (neither excess nor depletion). It's supplying O2
ions to balance the stoichiometry of primarily H & CO, and some unburnt
HCs, when rich. When lean of stoich, the current pump is simply removing
excess O2 from the sample chamber.

So yeah, it's never really "measuring" O2 per se, but *balancing* O2 in
the diffusion chamber, removing excess if lean, and providing what's
needed to make up for a depletion of O2, if rich. The amount needed to
balance IS a measure of either the amount of O2 in excess or the O2
that's missing, sotaspeak. From this, the AFR is computed.

HTH,
Gar


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