Method for feeding thermal energy into an exhaust emission control unit connected in the exhaust gas system of an internal combustion engine

摘要

The invention relates to a method for feeding thermal energy into an exhaust emission control unit (2) connected in the exhaust gas system of an internal combustion engine by heating the exhaust gas flowing to the exhaust emission control unit (2). Said exhaust gas is heated to a SET temperature. In said method, the exhaust gas discharged from the internal combustion engine is heated to the SET temperature by converting hydrocarbons (HCs) metered into the exhaust gas flow at two oxidation catalytic converters (7, 10) series-connected in the flow direction of the exhaust gas.

主权项

1. A method for feeding thermal energy into an exhaust emission control unit connected in an exhaust gas system of an internal combustion engine comprising the steps of:
heating an exhaust gas discharged from the internal combustion engine flowing to the exhaust emission control unit to a SET temperature by converting hydrocarbons (HCs) metered into the exhaust gas flow at two oxidation catalytic converters series-connected in the flow direction of the exhaust gas, the exhaust gas system splitting into a main and a secondary system, allowing the exhaust gas to be split into two streams; of which the first oxidation catalytic converter which is closer to the internal combustion engine in the flow direction of the exhaust gas is arranged in the secondary system and the second oxidation catalytic system connected downstream of the former in the exhaust gas system is arranged after the merging of the main and secondary systems; setting an HC metering for feeding hydrocarbons to the secondary system upstream of the first oxidation catalytic converter and/or an exhaust gas mass flow flowing through the secondary system as a function of a mass of the total exhaust gas flow discharged from the internal combustion engine, of an ACTUAL temperature and of the SET temperature of the exhaust gas flowing to the exhaust emission control unit, and by means of a pilot control variable which corresponds to or approach the current conditions, and which is taken from a pilot control diagram that takes into consideration the exhaust gas flow and the temperature rise to be achieved, repeatedly determining the ACTUAL temperature of the exhaust gas flowing to the exhaust emission control unit is, and
if a difference between the ACTUAL temperature and the SET temperature is noted, the setting of the HC metering and/or of the exhaust gas mass flow flowing through the secondary system is modified to reach the SET temperature, wherein temperature monitoring steps are repeated as often as needed until the SET temperature is reached.