Method for checking the plausibility of a NOx sensor in an SCR catalyst system

摘要

In a method for plausibility of a NOx sensor (62, 63) in an SCR catalyst system with at least one first SCR catalyst device (20) and at least one second SCR catalyst device (30) and in each case a metering point (40, 50) for a Reducing agent solution for the SCR catalyst devices (20, 30) upstream of the respective SCR catalyst device is the NOx plausibility sensor (62) either between the first SCR catalyst device (20) or the second SCR catalyst device (30) or to Plausibilizing NOx sensor (63) is located downstream of the second SCR catalyst device (30). For the plausibility check, a phase is carried out with a substoichiometric metering of the reducing agent solution for the first SCR catalytic converter device (20) or for the second SCR catalytic converter device (30), wherein the plausibilizing NOx sensor (62; 63) is located downstream of the SCR -Catalyst device (20; 30) is located with the substoichiometric dosage. The measurable signal values of the respectively to be plausibilized NOx sensor (62, 63) are compared with calculable or modelable signal values at a NOx conversion to be expected in the first SCR catalytic converter device (20) or in the second SCR catalytic converter device (30). In the case of a deviation taking account of predefinable tolerances, it is concluded that an implausibility of the respective NOx sensor (62, 63).