Page 259 - Methods For Monitoring And Diagnosing The Efficiency Of Catalytic Converters A Patent - oriented Survey

Emitec Gesellschafi fir Emissionstechnologie - Dr. Ing. H.c.F. Porsche AG 241

3) measuring and monitoring the temperature of the exhaust gases at the at least two regions
by means of planar (fig. 102) and/or approximately linear temperature sensors
4) measuring the temperature at least at one of the measurement locations integrally over an
approximately representative portion of at least one cross-sectional region and not in certain
spots (fig. 102)
5) performing the monitoring step by forming at least one temperature difference between
measured values at the at least two measurement locations
6) detecting a function of the catalytic converter, a control of the engine and a catalytic
converter regdating system from at least one of an algebraic sign, an absolute magnitude
and a behavior over time of the temperature difference.

The temperature sensors are re-calibrated after the engine has been stopped for a relatively
long period of time.

Fig. I02 (from DE4027207)

The method of W09114856 (1991) for monitoring the efficiency of a catalytic converter is
similar to that of W09114855 (1991) described above. The method uses additionally the
temperature difference indication of the sensors measured in the catalytic converter to control
the function of the engine and to protect the catalytic converter from overheating.