Various embodiments include a method for monitoring the tank content of a storage tank comprising: metering a fluid from the tank into the exhaust gas tract, wherein the fluid has a concentration with respect to a reducing agent; acquiring a current concentration value for the reducing agent; calculating a change in concentration of the reducing agent on the basis of the current concentration value in comparison with a stored concentration value; determining a current operating state of the vehicle to identify an operating state in which refueling cannot be carried out; and carrying out a plausibility check of the calculated change in concentration if the calculated change in concentration exceeds a predetermined threshold value and the operating state is identified. The plausibility check includes acquiring the current tank filling level of the fluid.

The present application provides a reductant dosing system for an SCR catalyst comprising an injector, a storage tank and a reductant pump arranged in a first fluid line between the storage tank and the injector for pumping reductant from the storage tank to the injector. The reductant dosing system comprises pressurizing means for pressurizing the storage tank.

An exhaust aftertreatment system may include a reductant supply and diluent supply conduits, an injector and a control module. The reductant supply conduit includes a first valve controlling a flow of reductant through the reductant supply conduit. The diluent supply conduit includes a second valve controlling a flow of diluent through the diluent supply conduit. The injector is in fluid communication with the reductant supply conduit and the diluent supply conduit and is configured to provide fluid to an exhaust stream. The control module may control the first valve to provide a targeted amount of reductant through the injector. The control module may control the second valve to maintain a fluid flow rate through the injector that is at or above a minimum flow rate threshold of the injector based on a difference between a flow rate through the reductant supply conduit and the minimum flow rate threshold.

Selective catalytic reduction systems are known and are generally included in exhaust systems of diesel engines in order to treat the exhaust gases of such engines. Such systems involve the introduction of diesel exhaust fluid (DEF) into exhaust gas flowing in an exhaust passage of an engine. When dosing DEF onto a hydrolysis catalyst in a SCR system, the DEF will under certain conditions cool the hydrolysis catalyst sufficiently to either slow down or effectively prevent ammonia release, which creates a lag or delay in the function of the hydrolysis catalyst. This limits the amount of control which can be exerted over ammonia storage in the SCR catalyst, and NOx conversion. In a first step, a set of measurement data is received from one or more sensors provided in the system. Subsequently, a first set of characteristics associated with a state of a component of the catalytic system, a second set of characteristics associated with an output of the catalytic system and a third set of characteristics associated with a bias and a scaling factor in the system are derived. In a third step, the derived sets of characteristics are used to control the catalytic system.

A determination of a quality of a reducing agent solution containing ammonia used to reduce nitrogen oxides involves actuating a metering unit that delivers metered quantities of reducing agent solution into an engine's discharged exhaust gas and determining an efficiency value that is at least correlated with the efficiency of the SCR catalytic converter and comparing the efficiency value to a predefinable limit value. If an efficiency value not corresponding to proper functioning of the SCR exhaust emission control system is identified by the comparison, a switch is made to a diagnostic mode in a second method step. If a predefinable deviation of the efficiency value from a limit value is identified after expiration of the second method step time period, a third method step is performed for conditioning the SCR catalytic converter. A fourth step involves an adaptation mode in which a deviation from the efficiency value is determined.

A level sensor assembly (10) for measuring physical properties indicative of a quality of a urea solution (AdBlue/DEF), where at least a portion of said level sensor assembly (10) is inserted in a tank (50), said level sensor assembly (10) comprises a header unit (12) mounted in an aperture of the tank (50); heating tubes (20) inserted in the tank for heating/thawing the urea solution in the tank (50) and one or more tubes (22) for suction of urea solution from the tank (50), said tubes (20,22) being connected to the header unit (12); and a level sensor (24,26) for measuring level of urea solution in the tank (50). Further, a detachable UQS sensor (30) is installed in the header unit (12), said UQS sensor (30) being at least partly submerged in a liquid pool (32) of urea solution in the header unit (12), and the liquid pool (32) in the header unit (12) comprises a compressible and/or expanding bottom (34).

A control apparatus controlling a controlled variable of a controlled object having a response lag characteristic using a combination of feedforward control method, response-specifying control method, and disturbance compensation method. An ECU of the apparatus calculates driver demand boost pressure for feedforward-controlling actual boost pressure as controlled variable, and calculates FB target pressure as value on which response lag characteristic of the actual value to the driver demand value is reflected. The ECU calculates error as difference between the actual and target values, and feedback correction term as sum of equivalent control input including disturbance estimated value and the error as variables and reaching law input, using equation defining relationship between the error, feedback correction term value, and disturbance estimated value, and response-specifying control algorithm, and then adds the correction term value to the driver demand value to thereby calculate demanded boost pressure as control input.

A method and a control assembly for operating an exhaust gas system of a motor vehicle is disclosed. Measuring values are evaluated, which indicate a content of nitrogen oxides in an exhaust gas downstream of a catalytic device. The catalytic device is adapted to diminish the content of nitrogen oxides in the exhaust gas produced by an engine of the motor vehicle. Based on the measuring values a quality of a reducing agent supplied to the catalytic device is assessed. The method includes determining whether reducing agent has been filled into a storage tank. A plurality of measuring values is captured during a predetermined period of time, and a magnitude and a frequency of the plurality of measuring values are taken into account to assess the quality of the reducing agent.

A connection head for being arranged in an orifice of a fluid tank with a return cavity in the form of a radial duct is provided. The return cavity overcomes the problems of the formation of air bubbles in the tank and enhances the functioning of the sensor in the tank.

A concentration detecting section detects a concentration of urea water and outputs the detected value. A determining section determines whether the urea water is suitable by using the detected value. A temperature detecting section detects temperatures of detection targets. The detection targets have temperatures that are different from one another during operation of an engine. The determining section is adapted to calculate a temperature difference between temperatures of a particular detection target and another detection target and start determining whether the urea water is suitable when a determination start condition including that the temperature difference is within a reference range is satisfied. The reference range is defined as a range of temperature differences in which it is determined that the urea water is in a quiescent state, which is suitable for the determination.