Page 278 - Methods For Monitoring And Diagnosing The Efficiency Of Catalytic Converters A Patent - oriented Survey
P. 278
260 Methods for Monitoring and Diagnosing the Efficiency of Catalytic Converters
-X
T
1,2 : non-catalytic temp. sensors
b
X
Xf
4,4': non-catalytic temp. sensors
53: catalytic temp. sensors
Fig. 1 12 (from DE2643739) Fig. 113 (from DE2643739)
The method of DE4211092 (1993) comprises three embodiments, which can be explained by
means of fig. 114, where a variation of temperature in the catalytic converter versus time is
shown. According to the invention, at a time interval of 5 min after start up of the engine a
new catalytic converter reaches its activation temperature.
The first embodiment comprises the following steps:
operating the engine under such conditions that the temperature of the catalytic converter
is lower than the activation temperature of a new converter
measuring the temperature over which the catalytic converter, heated by the exhaust gases,
begins to convert
comparing the temperature at which the catalytic converter begins to convert with a
predetermined value To, which lies above the activation temperature of a new catalytic
converter
determining that the catalytic converter is fhctional when the temperature at which the
catalytic converter begins to convert is smaller than the predetermined value To
The second embodiment comprises the following steps:
