Method for detecting oscillations of signals of reducing agent dosing system of exhaust gas aftertreatment system of diesel internal combustion engine of commercial vehicle, involves evaluating amplitude value for analyzing oscillations

摘要

The method involves evaluating signals (10) to be analyzed concerning to occurrence of maximum and/or minimum values (21, 22), by considering determined number (11) of values in an evaluation section of the signals. The maximum and/or minimum values are filtered by low pass transfer functions (31, 41) with time constants (32, 42), and the maximum and/or minimum values are reprocessed by differentiation of amplitude value (51), where the amplitude value is evaluated for analyzing oscillations of the signals. The amplitude value is filtered by a third low pass transfer function (61). An independent claim is also included for a diagnosing device for detecting oscillations of signals.