SCR METHOD FOR CHECKING THE PLAUSIBILITY OF A SENSOR SIGNAL OF A CONCENTRATION SENSOR ARRANGED IN AN SCR-CATALYTIC CONVERTER SYSTEM

摘要

The present invention relates to a method (100) for inspecting the validity of a sensor signal of a concentration sensor placed in an SCR catalyst converter system. The concentration sensor is composed and operated to measure the concentration of a UWS placed in a tank. For measuring the concentration, an ultrasonic signal generated from an ultrasonic wave source is transmitted through a pre-determined section, and the concentration of the UWS is calculated from the sound wave spreading time detected by the ultrasonic sensor. Further provided is an ultrasonic signal control unit to, when the ultrasonic sensor works properly, control the ultrasonic signal to keep a signal amplitude measured by the ultrasonic sensor within a pre-determined range of amplitude. One or more control variables of the ultrasonic signal control unit are used for inspecting the validity of the sensor signals of the concentration sensor (110).