Page 265 - Methods For Monitoring And Diagnosing The Efficiency Of Catalytic Converters A Patent - oriented Survey

Emitec Gesellschat? fir Emissionstechnologie - Dr. Ing. H.c.F. Porsche AG 247

I) measuring the temperature of the exhaust gases in a number of positions along the auxiliary
catalytic converter
2) evaluating the measured temperature values and/or their variation with time and/or their
correlation
3) using the method of W09114855 (1991) mentioned above to draw conclusions for the
degradation of the auxiliary catalytic converter
4) measuring the temperature of the exhaust gases inside the main catalytic converter
5) drawing conclusion for the condition of the main catalytic converter by using the same
evaluation means as the one of step 2.

sensor
temp, sensor
temp sensors
temP, sensors
/ (
main
catalyst

I
’-I evaluation
I
E.C. u. data’line - system @display
@ display

Fig. 106 (from W09314305)

The method of DE4227207 (1994) comprises the following steps:
I) measuring the temperature of the exhaust gases inside the catalytic converter during normal
operation of the catalytic converter (fig. 101)
2) modifying the operation conditions of the engine by varying an operation parameter of the
engine. Such parameters can be considered:
a) the concentration of hydrocarbons in the exhaust gases entering the catalytic
converter, or
b) the concentration of oxygen in the exhaust gases entering the catalytic
converter, or