Method and device for controlling an exhaust treatment system

The method as recited in one of the preceding claims,

• wherein the measured variable detected depends on the concentration of substances which are only partially converted or are not converted at all in the exhaust-gas aftertreatment system, the concentration of substances required for the conversion, and/or the concentration of unwanted intermediates formed.

The method as recited in one of the preceding claims,

• wherein the measured variable is compared with expected values in certain states of the internal combustion engine and/or the exhaust-gas aftertreatment system, and the quantity of reducing agent is corrected on the basis of this comparison.

The method as recited in one of the preceding claims,

• wherein a first variable, characterizing the quantity of ammonia in the exhaust gas downstream from the exhaust-gas aftertreatment system, is detected, the quantity of reducing agent being decreased when the first variable exceeds an upper threshold value, and/or the quantity of reducing agent being increased when the first variable falls below a lower threshold value.

The method as recited in one of the preceding claims,

• wherein a second variable, which characterizes the quantity of nitrogen oxides in the exhaust gas downstream from the exhaust-gas aftertreatment system, is detected, the quantity of reducing agent being decreased when the second variable falls below a lower threshold value and/or the quantity of reducing agent being increased when the second variable exceeds an upper threshold value.

The method as recited in one of the preceding claims,

• wherein the quantity of reducing agent is decreased when the first variable exceeds an upper threshold value, and/or the quantity of reducing agent is increased when the second variable exceeds an upper threshold value.

A device for controlling an exhaust-gas aftertreatment system, in particular for an internal combustion engine, the exhaust-gas aftertreatment system comprising at least one catalytic converter, a predefinable quantity of reducing agent being supplied to the exhaust-gas aftertreatment system as a function of the state of the internal combustion engine and/or the exhaust-gas aftertreatment system,

• wherein means are provided for adjusting the quantity of reducing agent supplied.

A computer program having program code means for performing all steps of any of claims 1 through 11 when the program is executed on a computer, in particular a control unit for an internal combustion engine.

A computer program product having program code means stored on a computer-readable data medium for performing the method as recited in any of claims 1 through 11 when the product is executed on a computer, in particular a control unit for an internal combustion engine.