Page 124 - Methods For Monitoring And Diagnosing The Efficiency Of Catalytic Converters A Patent - oriented Survey

106 Methods for Monitoring and Diagnosing the Etliciency of Catalytic Converters

fluctuation of Vz changes in accordance with the amount of oxygen stored in the catalytic
converter (saturation). As explained above, the amount of oxygen stored in the catalytic
converter can be calculated fi-om the rich gas inflow amount (the amount of HC and CO in the
exhaust gas flowing into the converter) and the rich gas outflow amount (the amount of HC
and CO in the exhaust gas flowing out fi-om the converter). Therefore, the rich gas inflow and
outflow amounts in each cycle are calculated in accordance with the outputs VI and V2,
respectively, and the deterioration of the catalytic converter is determined by comparing the
rich gas inflow amount and the rich gas outflow amount.

", (volts) -
a)
-
I ' 1 I reference
,
signal

catalyst absorbed saturating amount
:
% arnoum- A!------
b)
0
/
"2 (volts) NORMAL COWERTER
\
---------------- -____ ff reference
Rich
Lean signal

saturating amount
catalyst absorbed I
02 amount -
d)

DETERIORATED CONVERTER

signal
e)

time

Fig. 52 (fi-om EP0756073)