METHOD AND DEVICE FOR TESTING A LIQUID

摘要

A measuring device (2) for testing a liquid (4) used as reducing agent in connection with exhaust cleaning for exhaust gases from a combustion engine. A temperature sensor (6) measures the temperature in the liquid. An acoustic velocity measuring unit (8) measures the acoustic velocity in the liquid. The measured first temperature T1 for the liquid and a first acoustic velocity v1 for the liquid at the temperature T1 are delivered to a calculation unit (10). The temperature sensor determines a second temperature T2 for the liquid and delivers a temperature signal (12) to the calculation unit (10). That unit calculates the absolute value of a temperature difference ΔT between T1 and T2, i.e. ΔT=|T1−T2, and compares ΔT with a predetermined threshold value TTH. If ΔT exceeds TTH, the acoustic velocity measuring unit (8) determines a second acoustic velocity v2 for the liquid at the temperature T2 to deliver an acoustic velocity signal (14) to the calculation unit (10), which compares v1 and v2 with reference values vref1 and vref2 for a reference liquid at the respective temperatures T1 and T2. An approved indicating signal (18) is generated if the measured values v1 and v2 are within approved velocity ranges, but not approved if v1 and v2 are not within those ranges.

主权项

1. A method for testing a liquid used as a reducing agent in connection with exhaust cleaning for exhaust gases from a combustion engine, characterised in that the method comprises the steps of
a) determining a first temperature T1 for the liquid; b) determining an acoustic velocity v1 for the liquid at the first temperature T1; c) determining a second temperature T2 for the liquid; d) calculating the absolute value of a temperature difference ΔT between T1 and T2, i.e. ΔT=⊕T1−T2; e) comparing ΔT with a predetermined threshold value TTH, and if ΔT exceeds TTH, f) determining a second acoustic velocity v2 for the liquid at the temperature T2; g) comparing v1 and v2 with respective first and second velocity reference values vref1 and vref2 for a reference liquid at the respective temperatures T1 and T2, and h) generating an indicating signal on the basis of the results of the comparison, wherein the indicating signal is to the effect that the liquid is approved if the measured value v1 and v2 are within approved velocity ranges for the reference values, but not approved if v1 and v2 are not within said approved velocity ranges.