Abstract: A method for ascertaining an exhaust gas composition of an exhaust gas of an internal combustion engine with regard to an ammonia fraction and a nitrogen oxides fraction in an exhaust gas system including an SCR catalytic converter. The method includes detecting, using a sensor, a first signal whose magnitude is a function of the nitrogen oxides fraction of the exhaust gas upstream from the SCR catalytic converter, detecting using a sensor a second signal whose magnitude is a function of the ammonia fraction and the nitrogen oxides fraction of the exhaust gas downstream from the SCR catalytic converter, storing the two signals over an observation period, and ascertaining the ammonia fraction and optionally the nitrogen oxides fraction of the exhaust gas downstream from the at least one SCR catalytic converter using a calculation rule that uses the two signals during the observation period as input variables.

Abstract: A method for ascertaining an exhaust gas composition of an exhaust gas of an internal combustion engine with regard to an ammonia fraction and a nitrogen oxides fraction in an exhaust gas system including an SCR catalytic converter. The method includes detecting, using a sensor, a first signal whose magnitude is a function of the nitrogen oxides fraction of the exhaust gas upstream from the SCR catalytic converter, detecting using a sensor a second signal whose magnitude is a function of the ammonia fraction and the nitrogen oxides fraction of the exhaust gas downstream from the SCR catalytic converter, storing the two signals over an observation period, and ascertaining the ammonia fraction and optionally the nitrogen oxides fraction of the exhaust gas downstream from the at least one SCR catalytic converter using a calculation rule that uses the two signals during the observation period as input variables.

Abstract: A method of determining a suitable evaluation time for a diagnosis method for the diagnosis of a component, wherein the diagnosis method is based on at least one measured sensor value and at least one modeled comparative value (cOBDsim), wherein the method comprises: replacing, in the diagnosis method, at least one measured sensor value with a calculated model value (cBPU), where the model (20) for the calculation of the model value is a model of the component in a state that is to be recognized by the diagnosis method; executing (102, 104, 106) the diagnosis method with the calculated model value; obtaining a result value (aOBDsim) of the diagnosis method; repeating the preceding steps until the result value attains a defined threshold value; and fixing the suitable evaluation time in the diagnosis method as the time after which the result value has attained the threshold value.

Abstract: A method of monitoring an SCR catalyst in which an area factor (a) of the SCR catalyst is ascertained by means of an observer. It is concluded that there is a fault in the SCR catalyst when a comparison shows that the area factor (a) has gone below a threshold value (S).

Abstract: A method and an apparatus for determining the fill level of a fluid (2) in a tank (1), wherein a propagation time of an ultrasonic signal between an ultrasound element (4) and a reflection at the surface (3) of the fluid (2) is measured. A first, single reflection and a second, double reflection are evaluated, wherein the measurement of the reflections is carried out with a measurement setting with an excitation energy of the ultrasonic signal and a sensitivity. The sensitivity is indicated by a gain and a comparison value (13). Via measurements with different measurement settings, a suspected first reflection and a suspected second reflection are located and a plausibility check is carried out of the propagation times of the first and second reflections with respect to each other.

Abstract: In a method for heating an exhaust system of a combustion engine of a motor vehicle, the exhaust system comprises at least two components for exhaust gas cleaning. For at least one component, a temperature regulation is provided for heating the component while using a heating operation mode. For the heating of the exhaust system, a heating operation is used via a pulse control with heating pulses (101) and heating pauses (102), which switches between a heating operation mode and a normal operation without heating measures.

Abstract: A method of monitoring an SCR catalyst in which an area factor (a) of the SCR catalyst is ascertained by means of an observer. It is concluded that there is a fault in the SCR catalyst when a comparison shows that the area factor (a) has gone below a threshold value (S).

Abstract: A method of determining a suitable evaluation time for a diagnosis method for the diagnosis of a component, wherein the diagnosis method is based on at least one measured sensor value and at least one modeled comparative value (cOBDsim), wherein the method comprises: replacing, in the diagnosis method, at least one measured sensor value with a calculated model value (cBPU), where the model (20) for the calculation of the model value is a model of the component in a state that is to be recognized by the diagnosis method; executing (102, 104, 106) the diagnosis method with the calculated model value; obtaining a result value (aOBDsim) of the diagnosis method; repeating the preceding steps until the result value attains a defined threshold value; and fixing the suitable evaluation time in the diagnosis method as the time after which the result value has attained the threshold value.

Abstract: In a method for heating an exhaust system of a combustion engine of a motor vehicle, the exhaust system comprises at least two components for exhaust gas cleaning. For at least one component, a temperature regulation is provided for heating the component while using a heating operation mode. For the heating of the exhaust system, a heating operation is used via a pulse control with heating pulses (101) and heating pauses (102), which switches between a heating operation mode and a normal operation without heating measures.

Abstract: In a method for monitoring an SCR catalyst, in particular for monitoring the storage capacity of the SCR catalyst for ammonia, superstoichiometric metering (69) of reducing agents into the SCR catalyst is performed for diagnostic purposes, and the storage capacity of the SCR catalyst is inferred in accordance with at least one characteristic value, which is dependent on the nitrogen oxide conversion rate of the SCR catalyst. In this method, a conditioning phase (67) for setting a specifiable operating point (68) is carried out before the superstoichiometric metering (69) of reducing agents.

Abstract: A method for operating an exhaust gas system for an internal combustion engine, in which the exhaust gas system includes at least one first catalytic coating and at least one second catalytic coating, the second catalytic coating being situated in the exhaust gas flow downstream from the first catalytic coating. An additional quantity of hydrocarbons is occasionally introduced into the exhaust gas upstream from the first catalytic coating so that a heat-generating reaction may take place in the second catalytic coating. With the aid of at least one temperature sensor and/or at least one hydrocarbon sensor and/or at least one lambda sensor upstream and/or downstream from the second catalytic coating, at least one property of the exhaust gas is ascertained which characterizes a reaction of the second catalytic coating due to the additional quantity of hydrocarbons.

Abstract: A method for operating an exhaust gas system for an internal combustion engine, in which the exhaust gas system includes at least one first catalytic coating and at least one second catalytic coating, the second catalytic coating being situated in the exhaust gas flow downstream from the first catalytic coating. An additional quantity of hydrocarbons is occasionally introduced into the exhaust gas upstream from the first catalytic coating so that a heat-generating reaction may take place in the second catalytic coating. With the aid of at least one temperature sensor and/or at least one hydrocarbon sensor and/or at least one lambda sensor upstream and/or downstream from the second catalytic coating, at least one property of the exhaust gas is ascertained which characterizes a reaction of the second catalytic coating due to the additional quantity of hydrocarbons.

Abstract: A method is provided for monitoring an SCR catalytic converter (12), in which method the NH3 storage capacity of the SCR catalytic converter (12) is monitored. The SCR catalytic converter (12) is initially filled in an overdosing phase with a superstoichiometric reducing agent dosing up to the maximum NH3 storage capacity. The catalytic converter is subsequently acted on in an underdosing phase with a reducing agent dosing which is reduced in relation to a normal dosing or is absent. The NH3 storage capacity is indirectly determined during the underdosing phase by determining at least one characteristic value which is dependent on the NOx conversion rate. According to the invention, to detect NH3 slippage (25), which indicates the transition from the overdosing phase to the underdosing phase, a variable which is characteristic of the NOx conversion is continuously measured during the overdosing phase, and in the event of a fall in the NOx conversion, it is inferred that NH3 slippage (25) is present.

Abstract: A method is provided for monitoring an SCR catalytic converter (12), in which method the NH3 storage capacity of the SCR catalytic converter (12) is monitored. The SCR catalytic converter (12) is initially filled in an overdosing phase with a superstoichiometric reducing agent dosing up to the maximum NH3 storage capacity. The catalytic converter is subsequently acted on in an underdosing phase with a reducing agent dosing which is reduced in relation to a normal dosing or is absent. The NH3 storage capacity is indirectly determined during the underdosing phase by determining at least one characteristic value which is dependent on the NOx conversion rate. According to the invention, to detect NH3 slippage (25), which indicates the transition from the overdosing phase to the underdosing phase, a variable which is characteristic of the NOx conversion is continuously measured during the overdosing phase, and in the event of a fall in the NOx conversion, it is inferred that NH3 slippage (25) is present.