Method for operating a reductant metering process of an SCR catalytic converter system, and corresponding SCR catalytic converter system

摘要

The invention relates to an SCR catalytic convertor system and a method for operating a reductant metering process of an SCR catalytic converter system (14) of an internal combustion engine (10), wherein the SCR catalytic converter system (14) has a first SCR exhaust emission control device (16), an SCR catalytic converter (18) arranged downstream of the SCR exhaust emission control device, and a reductant metering device (20) for metering a reductant into the exhaust gas flow upstream of the first SCR exhaust emission control device (16), wherein the reductant metering process is controlled at least depending on a temperature of the first SCR exhaust emission control device (16) and of the SCR catalytic converter (18) arranged downstream, wherein (I) if the temperature of the first SCR exhaust emission control device (16) is greater than or equal to a predetermined minimum temperature (T_SPF min) and the SCR catalytic converter (18) arranged downstream is less than a predetermined minimum temperature (T_SCR min), the reductant metering process occurs in a first operating mode in such a way that a reductant filling level (NH3_SPF) of the first SCR exhaust emission control device (16) is less than the maximum reductant filling level (NH3_SPF_max) of the first SCR exhaust emission control device, and (II) if the temperature of the SCR catalytic converter (18) arranged downstream is greater than or equal to the minimum temperature (T_SCR min) of the SCR catalytic converter arranged downstream, the reductant metering process occurs at least at times in a second operating mode in such a way that the reductant filling level (NH3_SPF) of the first SCR exhaust emission control device (16) is greater than the maximum reductant filling level (NH3_SPF_max) of the first SCR exhaust emission control device, such that a reductant penetration passing through the first SCR exhaust emission control device (16) hits the SCR catalytic converter (18) arranged downstream.

主权项

1. A method for carrying out a reductant metering process of an SCR catalytic converter system of an internal combustion engine,
wherein the SCR catalytic converter system has a first SCR exhaust-gas treatment unit, an SCR catalytic converter located downstream from the first SCR exhaust-gas treatment unit, and a reductant metering device for metering a reductant into the exhaust-gas stream upstream from the first SCR exhaust-gas treatment unit, whereby the reductant metering process is controlled at least as a function of the temperature of the first SCR exhaust-gas treatment unit and of the downstream SCR catalytic converter, whereby if the temperature of the first SCR exhaust-gas treatment unit is higher than or equal to a first prescribed minimum temperature as defined as T_SPF_min and if the temperature of the downstream SCR catalytic converter is lower than a second prescribed minimum temperature as defined as T_SCR_min, the reductant metering process takes place in a first mode of operation in such a way that the reductant filling level of the first SCR exhaust-gas treatment unit is lower than its maximum reductant filling level, and if the temperature of the downstream SCR catalytic converter is higher than or equal to T_SCR_min, the reductant metering process takes place in a second mode of operation in such a way that the reductant filling level of the first SCR exhaust-gas treatment unit is higher than its maximum reductant filling level, so that a reductant breakthrough that is passing the first SCR exhaust-gas treatment unit reaches the downstream SCR catalytic converter.