toyota 02 SAE paper

[zack]

Garfield,

Hmm, I was reading similar papers about using O2 sensor in current mode
(biased with a small voltage <1 volts), and the temperature sensitivity
was very low, so all you really need is a very nice voltage source (very
low impedance) and you're set.  Not of caution, though, that the current
output is proportional to pressure, which may or may not suck, depending
on the application.

Z

garfield at pilgrimhouse.com wrote:
> 
> On Thu, 12 Mar 1998 17:22:29 +0000, xxalexx at ix.netcom.com wrote:
> 
> >Instead of measuring voltage across the electrodes like regular
> >sensor a  constant voltage of 0.5 +-0.2 is  applied and current
> >measured. The graphs show:
> >a/f     current (mA)
> >11     -12
> >12     -11
> >13     -6
> >14     -2
> >14.5   0
> >16     3
> >18     7
> >23     13
> 
> Very promising; I dumped those numbers into excel and what I see doesn't
> look very kinky at all. Each of the two legs on either side stoich look
> like they could easily be linearized with a few segments of piecewise
> linear opamp approximation. Both legs look like they have significant
> spans/segments of almost linear shape, until you get fairly far away
> from stoich. These days with 4 opamps per chip, it takes only a few
> parts to match the curve if it's nice and reasonable, like this one
> appears to be, judging from just the numbers above. Good summary. Geez,
> feast or famine. Now it looks like we might have 3 candidates, the
> Bosch, the NTK, and now the ND!
> 
> Now the real question; I couldn't tell from your review comments just
> how Temp sensitive these curves are likely to be. That appears to be the
> only possible fly in the ointment; it sounded like Temp maybe wasn't
> much an issue. Is that correct? If so, this sensor approaches the "too
> good to be true" category. Simple, fairly linear on either leg, there's
> gotta be a gotcha, unless Miss Nature is suddenly and unusually charmed
> by our presence, and want's to "help" us. Heh, NAH!
> 
> Garfield the cynic
> 
> P.S. Anyone have ANY clue as to a part no. for this ND wonder? I guess I
> lead a sheltered life; dunno what an LEV Toy car even IS. Is it their
> new anti-gravity model, that LEVitates? OK, it was just a wild guess.