toyota 02 SAE paper

[xxalexx at ix.netcom.com]

review of sae paper 970843
The sensor looks like regular o2 sensor with a diffusion layer added.
The diffusion layer is temperature or pressure independent depending
on pore size. Automotive use pressure dependence thus no temperature
dependence with diffusion layer.
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   

Calibration of sensor was not discussed.
A equation relating sensor materials,dimensions, temperature and
pressure to current ouput is given.
Possible deviation from above curve can be determined if 
manufacturing tolerance and temperature dependence
is significant.
The operating temperature is over 700 C as compared to 400 C
for regular O2 sensor.
The equation is basically the inverted nerst equation for regular O2
sensor with addition of diffusion layer, and a  absolute P/T 
dependence.  Since diffusion layer is temperature independent, 
temperature calibration should not be needed at operating 
temperature of over 700 C as compared to 400 C for regular O2 sensor.
alex