Method for operating an internal combustion engine

Abstract

A method for operating an internal combustion engine (10) which has an exhaust system (12) through which exhaust gas from the internal combustion engine (10) flows, with at least one oxidation catalyst (16) as the first aftertreatment element and with at least one particulate filter (18) as the second aftertreatment element, in which, for carrying out a cleaning mode assigned to at least one of the aftertreatment elements (16, 18), at least one temperature (T) of the exhaust gas prevailing upstream of the at least one aftertreatment element (16, 18) is set for a predefinable period of time (32), which lies in a first temperature range, the temperatures of which are lower than the temperatures of a second temperature range for regenerating the particulate filter (18), characterized in that, in the cleaning mode, hydrocarbons deposited on the at least one aftertreatment element (16, 18) are removed by the at least one aftertreatment element (16, 18).18) are at least partially removed, wherein the first temperature range extends from 520 Kelvin inclusive to 570 Kelvin inclusive, and a second cleaning mode is carried out after the cleaning mode, in which sulfur deposited on the at least one aftertreatment element (16, 18) is at least partially removed from the at least one aftertreatment element (16, 18), wherein a temperature (T) of the exhaust gas prevailing upstream of the at least one aftertreatment element (16, 18) is set, which lies in a third temperature range, the temperatures of which are greater than the temperatures of the first temperature range, and a conditioning mode is carried out between the cleaning modes and before the regeneration, in which a temperature (T) of the exhaust gas prevailing upstream of the particulate filter (18), in particular upstream of the particulate filter (18) and downstream of the oxidation catalyst (16), is set.which lies in a fourth temperature range, the temperatures of which are higher than the temperatures of the first temperature range and lower than the temperatures of the second temperature range.

Claims

[1] Method for operating an internal combustion engine (10), which has an exhaust system (12) through which exhaust gas from the internal combustion engine (10) can flow, with at least one oxidation catalyst (16) as a first aftertreatment element and with at least one particulate filter (18) as a second aftertreatment element, in which method, in order to carry out a cleaning mode assigned to at least one of the aftertreatment elements (16, 18) over a predeterminable period of time (32), at least one temperature (T) of the exhaust gas prevailing upstream of the at least one aftertreatment element (16, 18) is set, which temperature lies in a first temperature range, the temperatures of which are lower than temperatures of a second temperature range for regenerating the particulate filter (18), characterized bythat in the cleaning mode, hydrocarbons deposited on the at least one aftertreatment element (16, 18) are at least partially removed from the at least one aftertreatment element (16, 18), wherein the first temperature range extends from 520 Kelvin up to and including 570 Kelvin, and a second cleaning mode is carried out after the cleaning mode, in which sulfur deposited on the at least one aftertreatment element (16, 18) is at least partially removed from the at least one aftertreatment element (16, 18), wherein a temperature (T) of the exhaust gas prevailing upstream of the at least one aftertreatment element (16, 18) is set, which temperature lies in a third temperature range, the temperatures of which are greater than the temperatures of the first temperature range, and a conditioning mode is carried out between the cleaning modes and before the regeneration, in which a conditioning mode upstream of the particulate filter (18),in particular upstream of the particulate filter (18) and downstream of the oxidation catalyst (16), the prevailing temperature (T) of the exhaust gas is set, which lies in a fourth temperature range, the temperatures of which are greater than the temperatures of the first temperature range and lower than the temperatures of the second temperature range. [2] Method according to claim 1, characterized by that the exhaust gas is heated in cleaning mode at a heating rate of maximum 10 Kelvin per minute. [3] Method according to one of claims 1 or 2, characterized by that the cleaning mode is carried out as a function of at least one loading value characterizing the deposition of hydrocarbons on at least one aftertreatment element (16, 18), which is calculated by means of a model. [4] Method according to claim 1, characterized by that in conditioning mode the temperature of the exhaust gas is set to 670 Kelvin. [5] Method according to one of claims 1 or 4, characterized by that the exhaust gas is heated in the second cleaning mode at a heating rate of 20 to 200 Kelvin per minute. [6] Method according to one of the preceding claims, characterized by that a regeneration of the particle filter (18) is carried out after the cleaning mode, wherein a temperature (T) of the exhaust gas prevailing upstream of the particle filter (18), in particular upstream of the particle filter (18) and downstream of the oxidation catalyst (16), is set which lies in the second temperature range.

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