Two Questions

[Don DRI05 Ricciardiello]

Thanks Pete,

That pretty much covers it for me without beinging too tecchie!

Don




From: Peter Gargano <peter at techedge.com.au>@diy-efi.org on 29/10/2001 08:23
      ZE11

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To:   diy_efi at diy-efi.org
cc:
Subject:  Re: Two Questions


Don DRI05 Ricciardiello wrote:
>
> Looking at the specs of the Bosch LSM11 sensor particularly the
> characteristic curve on ftp://ftp.diy-efi.org/incoming/Bosch_lsm11.pdf
> would this unit be considered a true wide-band sensor?

I assume that Bosch designed this sensor to have as wide a
"switching" characteristic as is possible using the same
technology as other switching sensors. Bosch, and a lot of
people who make WB meters using this sensor, would like to
think it's a WB sensor, but it does use narrow band or switching
technology, and well designed electronics can make use of the
output to give an indication of AFR (or Lambda).

> Secondly, (warning: newbie alert) irrespective of sensor types, seeing as
> they all produce a voltage, why do you need all the associated electronic
> wizardry with it?

The NTK/Honda sensor is fundamentally different. Recent posts have
correctly described the sensor as a narrow band sensor combined
(sandwiched) in with a pump cell that can alter the concentration of
oxygen within the sandwich. The "associated electronics" are
required to provide a feedback signal to the oxygen pump cell based
on the output of the integral narrow band sensor. The feedback tries
to maintain a "stoic" output from the narrow band sensor. The effort
required to force the pump cell to balance the oxygen concentration
is a measure of the oxygen concentration in the cell at the time.
This current (called Ip or pump current) is a measure of how far
away from stoic the volume of gas in the sandwich is. The electronics
convert the Ip to a Vout - and the calibration resistor in the connector
of the sensor is used to allow for variations in construction of
the sensor that require more or less pump current for the same cell
balance.

Peter
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