Abstract: A method (200) for determining an amount of hydrocarbons in an exhaust gas (10) downstream of a lean-operation internal-combustion engine (110), comprising the following steps: observing a first catalyst heating mode of the internal-combustion engine (110) at a high catalyst temperature, wherein a predefinable amount of fuel having a predominantly non-combusting portion is introduced into a combustion chamber of the internal-combustion engine (110); determining an actual temperature change downstream of an oxidation catalyst (120) downstream of the internal-combustion engine (110) during the first catalyst heating mode; and determining the amount of hydrocarbons (cHC) in the exhaust gas (10) upstream of the oxidation catalyst (120) based on the actual temperature change. Furthermore, a computing unit (140) and a computer program for carrying out such a method (200) are proposed.

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 (200) for determining an amount of hydrocarbons in an exhaust gas (10) downstream of a lean-operation internal-combustion engine (110), comprising the following steps: observing a first catalyst heating mode of the internal-combustion engine (110) at a high catalyst temperature, wherein a predefinable amount of fuel having a predominantly non-combusting portion is introduced into a combustion chamber of the internal-combustion engine (110); determining an actual temperature change downstream of an oxidation catalyst (120) downstream of the internal-combustion engine (110) during the first catalyst heating mode; and determining the amount of hydrocarbons (cHC) in the exhaust gas (10) upstream of the oxidation catalyst (120) based on the actual temperature change. Furthermore, a computing unit (140) and a computer program for carrying out such a method (200) are proposed.

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 detects a manipulation of an exhaust gas system, in which measured values are sent to an external checking unit by a control unit of the exhaust gas system. In the external checking unit, an evaluation of the exhaust gas system as “manipulated” or as “not manipulated” takes place. Model values are formed in the control unit, which are at least partially formed from the measured values which are sent to the external checking unit. The external checking unit takes the model values and the measured values into consideration in the evaluation of the exhaust gas system.

Abstract: A method and a control unit for checking an exhaust gas system in a vehicle. A control unit in the vehicle receives data from sensors of the vehicle and sends out control commands to final control elements of the vehicle. The control unit is in communication connection with an external computer located outside of the vehicle. The external computer causes the control unit to make an active intervention in the exhaust gas system by actuating final control elements of the vehicle. The control unit receives sensor data from the exhaust gas system, which it forwards to the external computer. Based on the sensor data from the sensors, the external computer rates the exhaust gas system as “OK” or “manipulated”.

Abstract: A method detects a manipulation of an exhaust gas system, in which measured values are sent to an external checking unit by a control unit of the exhaust gas system. In the external checking unit, an evaluation of the exhaust gas system as “manipulated” or as “not manipulated” takes place. Model values are formed in the control unit, which are at least partially formed from the measured values which are sent to the external checking unit. The external checking unit takes the model values and the measured values into consideration in the evaluation of the exhaust gas system.

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: The invention concerns a method for monitoring an SCR catalytic converter in an exhaust line of an internal combustion engine, into which a reducing agent solution for the reduction of nitrogen oxides is dosed, wherein the SCR catalytic converter is diagnosed as defective if a measured variable is below a corresponding threshold and wherein the diagnosis of the SCR catalytic converter occurs when enabling criteria are met, wherein the enabling criteria are selected depending on a BPU model and a WPA model such that when the SCR catalytic converter (3) conforms to the BPU model, ammonia slip occurs through this SCR catalytic converter (3), and when the SCR catalytic converter corresponds to the WPA model, no ammonia slip occurs through this SCR catalytic converter.

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: A method for monitoring a nitrogen oxide storage catalyst in an exhaust system of an internal combustion engine, in which a reduction of nitrogen oxides is carried out by means of a reducing agent is disclosed. During a regeneration of the nitrogen oxide storage catalyst, the following steps are carried out: A measurement is carried out, from which a slip rate of the reducing agent not absorbed in the nitrogen oxide storage catalyst is ascertained. In addition, at least one expected value for the slip rate of the reducing agent is ascertained from at least one model. Subsequently, a computation of a monitoring variable is carried out by means of the slip rate of the reducing agent ascertained from the measurement and the at least one expected value for the slip rate of the reducing agent. Finally, a diagnosis of the storage capacity of the nitrogen oxide storage catalyst is carried out on the basis of the monitoring variable.

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: The invention concerns a method for monitoring an SCR catalytic converter in an exhaust line of an internal combustion engine, into which a reducing agent solution for the reduction of nitrogen oxides is dosed, wherein the SCR catalytic converter is diagnosed as defective if a measured variable is below a corresponding threshold and wherein the diagnosis of the SCR catalytic converter occurs when enabling criteria are met, wherein the enabling criteria are selected depending on a BPU model and a WPA model such that when the SCR catalytic converter (3) conforms to the BPU model, ammonia slip occurs through this SCR catalytic converter (3), and when the SCR catalytic converter corresponds to the WPA model, no ammonia slip occurs through this SCR catalytic converter.

Abstract: A method for monitoring a nitrogen oxide storage catalyst in an exhaust system of an internal combustion engine, in which a reduction of nitrogen oxides is carried out by means of a reducing agent is disclosed. During a regeneration of the nitrogen oxide storage catalyst, the following steps are carried out: A measurement is carried out, from which a slip rate of the reducing agent not absorbed in the nitrogen oxide storage catalyst is ascertained. In addition, at least one expected value for the slip rate of the reducing agent is ascertained from at least one model. Subsequently, a computation of a monitoring variable is carried out by means of the slip rate of the reducing agent ascertained from the measurement and the at least one expected value for the slip rate of the reducing agent. Finally, a diagnosis of the storage capacity of the nitrogen oxide storage catalyst is carried out on the basis of the monitoring variable.

Abstract: In a method for diagnosing an SCR catalyst system of an internal combustion engine, the SCR catalyst system comprises at least one first SCR catalyst device (20) and at least one second SCR catalyst device (30). A first injection position upstream of the first SCR catalyst device (20) in the form of a first metering device (40) is provided for injecting liquid reducing agent for the SCR catalyst devices (20, 30). A second injection position between the two SCR catalyst devices (20, 30) in the form of a second metering device (50) is furthermore provided. Both SCR catalyst devices (20, 30) are monitored in a differentiated way by means of active and passive diagnostic methods.

Abstract: In the case of a method for operating an exhaust gas aftertreatment system of a motor vehicle, the exhaust gas aftertreatment system comprises at least one NOx storage catalyst (10) and at least one SCR catalyst (30). According to the invention, when an inadequate function of the NOx storage catalyst (10) or of the SCR catalyst (30) is identified, at least one auxiliary measure is initiated which leads to a reduction of the NOx emissions of the motor vehicle.