Page 187 - Methods For Monitoring And Diagnosing The Efficiency Of Catalytic Converters A Patent - oriented Survey

Chapter 1.9

Siemens Automotive SA - Siemens AG

The method of W09309335 (1993) and US5487269 (1996) is applied for the layout of fig. 76
and is explained with the help of fig. 77.

Fig. 76 shows an internal combustion engine equipped with an air filter, an air inlet duct and a
throttle valve for regulating the inlet air flow rate, downstream of which there is an inlet
pressure sensor which supplies a signal to a computer (CPU). A sensor for the speed of the
engine, fixed facing a flywheel of this engine, supplied a second signal to the computer. The
latter receives a third signal supplied by an oxygen probe 1 placed in the pipe of the exhaust
gases of the engine, upstream of a three-way catalytic converter.
The computer comprises electronic signal processing, calculation and memory means necessary
for controlling the opening time I,, or injection time, of one or more &el injectors. The
assembly constitutes a closed-loop regulation (feedback) device for this injection time, the loop
being closed by the third signal supplied by the oxygen probe 1.

169