A method for determining an amount of liquid removed from a tank per unit time includes discontinuously feeding the liquid to exhaust gas of an internal combustion engine by at least feeding the liquid through an injection line into the exhaust gas, measuring pressures simultaneously at least at two points in the injection line and determining an amount of liquid fed in per unit time from the measured pressures. The amount of liquid removed between a first point in time and a second point in time is further derived by integrating the amounts of liquid removed per unit time over a period of time from the first point in time to the second point in time. The method allows the precise consumption of the liquid to be calculated and the remaining amount of liquid in the tank to be additionally determined. On-board diagnosis is further possible with the method.

The invention relates to a control method that allows the mean quantity of nitrogen oxides per kilometer covered emitted by a vehicle fitted with an internal combustion engine associated with a post-treatment system to be kept below a predefined fixed threshold, for any journey made by the vehicle. The mean quantity emitted over a fixed elementary distance that has just been covered by the vehicle is calculated iteratively, together with a long-term conformity factor which is equal to the mean quantity emitted over the entire distance covered since the start of the journey. When it is found that the long-term conformity factor is above the threshold, the engine and/or the post-treatment system is regulated in such a way as to obtain, over the next fixed elementary distance, a mean quantity of nitrogen oxides per kilometer that is lower than the threshold value FC, for example equal to 90% of the threshold, whatever the engine operating point. Thus, the long-term conformity factor converges towards the threshold.

Disclosed is a method for diagnosing functionality of dosing units of a fluid dosing system comprising at least two dosing units, a tank unit for holding a fluid, and a pump unit for pressurizing the fluid for the dosing units. The method comprises determining a first hydraulic stiffness value on the basis of first pressure variations and determining a second hydraulic stiffness value on the basis of said second pressure variations. The first hydraulic stiffness value and second hydraulic stiffness value are compared. In a case where the first hydraulic stiffness value and second hydraulic stiffness value differ to a certain extent, concluding that malfunction of at least one of said dosing units is at hand, and in a case where the first hydraulic stiffness value and the second hydraulic stiffness value do not differ to said certain extent, concluding that the first and second dosing units function as intended.

A method for operating a motor vehicle having an exhaust gas aftertreatment device involves an on-board electronic computing device receiving consumption information characterizing consumption of a reducing agent by the exhaust gas aftertreatment device and tank information characterizing a filling level of a reducing agent tank. Tank information is evaluated together with the consumption information with regard to a divergence, and upon determination of the divergence between the tank information and the consumption information, error information is stored in a blockchain characterizing the motor vehicle, and an action of the motor vehicle is triggered.

A method for controlling a return valve of an exhaust system and to an exhaust system with a control unit which is configured to carry out the method. The method is based on the object of avoiding an overpressure in the line system for urea solution as a result of a reduction in the injection rate. The method includes the steps of determining whether one or more of the following states are present during the operation of the exhaust system: a) an injection rate per unit of time of urea solution of the dosing valve is less than or equal to a predefined injection limit, b) a pressure measured by the pressure sensor in the line system overshoots a predefined first upper pressure limit (P2). The return valve is opened for a first predefined opening duration (Δt1) if states a) and b) are present and at least one of the states has already been present for at least a predefined period of time (Δta). The return valve is closed after the first predefined opening duration (Δt1) has elapsed.

A heavy duty truck includes a diesel engine that generates an exhaust gas flow and an exhaust after-treatment system for treatment of the exhaust gas flow. The exhaust after-treatment system includes at least one temperature sensor at an underbody SCR system within the exhaust after-treatment system and a DEF injector upstream of a close-coupled SCR system within the exhaust after-treatment system. The DEF injector is operated to inject DEF into the exhaust gas flow at a rate that varies as a function of a temperature measured by the temperature sensor.

An urea injection control system for an internal combustion engine, specifically adapted to apply a scheme for decreasing a NOx level downstream of a selective catalytic reduction catalyst of an ICE related exhaust gas aftertreatment system. The present disclosure also relates to a corresponding computer implemented method and a computer program product.

Methods and/or systems for operating an exhaust-gas aftertreatment system of an internal combustion engine include: setting the internal combustion engine to a diagnostic operating mode with relevant diagnostic operating parameters of the internal combustion engine are set to correspond with diagnostic default values; inducing a targeted, defined NH.sub.3 and/or NO.sub.X concentration change upstream of the filter; measuring the NH.sub.3 and/or NO.sub.X concentration change downstream of the filter; providing a correlating concentration comparison value; evaluating the concentration change on the basis of the respective concentration comparison value and predefined limit values; and diagnosing the SCR particle filter as defective if the evaluation yields that the concentration comparison value has overshot a predefined limit value.

A system comprising an aftertreatment system comprising: a catalyst member, and a first exhaust conduit upstream of the catalyst member; a first temperature sensor operatively coupled to the catalyst member; a flow sensor coupled to the first exhaust conduit; and a controller. The controller determines a temperature of the catalyst member, a flow rate of exhaust within the first exhaust conduit, and a space velocity of the exhaust within the catalyst member. The controller determines a first degradation value indicative of a degradation of the catalyst member. The controller determines a first difference between the first degradation value and a first degradation reference value and a second difference between the first degradation value and a second degradation reference value. After determining that the first difference is less than the second difference, the controller selects a first calibration metric. The controller determines a first efficiency value associated with the catalyst member.

The present invention relates to a method for diagnosing aftertreatment of exhaust gases resulting from combustion, wherein at least a first substance resulting from said combustion is reduced by supplying additive to an exhaust gas stream resulting from said combustion and use of a first reduction catalytic converter. The method includes: estimating an accumulated expected reduction of said first substance during a first period of time, determining an accumulated actual reduction of said first substance during a period of time at least substantially overlapping said first period of time, and generating a signal indicating a fault in said reduction of said first substance when said accumulated actual reduction differs from said accumulated expected reduction by a predetermined difference in occurrence of said first substance. The invention also relates to a corresponding system.