Page 248 - Methods For Monitoring And Diagnosing The Efficiency Of Catalytic Converters A Patent - oriented Survey

230 Methods for Monitoring and Diagnosing the Efficiency of Catalytic Converters

where:
G is a parameter that allows to determine the convergence speed of the method,
gt) is a hnction of the sign of (v). This hnction can be expressed as:

f(f) = sign v(0, or

8) solving the system of the above mentioned equations in an iterative way in order to obtain
such values of (x), (y) and (z) that suppress the difference between the calculated (z) and
measured concentration of oxygen (v) of the exhaust gas downstream of the catalytic
converter
9) determining the condition of the catalytic converter by comparing the maximum quantity of
oxygen (y) that can be stored in the catalytic converter calculated at step 8 with a
predetermined threshold
The method can be also used with catalytic converters that store nitrogen oxides instead of
oxygen.

0 Deutsche Fernsprecher GmbH Marburg

The method of DE381 1732 (1989) presents an electric circuit used for fhctionally testing
catalytic converters of motor vehicles. The circuit comprises a controllable switch for applying
normal h probe voltage or test voltage to a h probe installed upstream of the catalytic
converter.

0 Other Methods

Other methods of monitoring catalytic converters by means of oxygen sensors may be found in
the following disclosures:

RU2059080 (1996) by Elkrr Stock Co. and in [32].