Disclosed is a method for preventing a risk of freezing in a device for supplying reducing agent to a selective catalytic reduction system in an exhaust line, a freezing temperature specific to the agent being stored in memory, the system including a controller operating the system and emitting pulses to an injector, the controller being inactive when the engine is switched off. With the combustion engine switched off, the controller is woken up at predetermined intervals to initiate an emission of a specific electric pulse to the injector with measurements of a current-strength and voltage of the electric pulse providing a value of the electrical resistance of the injector. A temperature of the reducing agent at the injector is estimated as a function of the measured resistance and, when at least the temperature thus estimated is below the freezing temperature, a purge of the device is initiated.

An apparatus includes a pump, a delivery mechanism in fluid communication with the pump, and a controller communicatively coupled to the pump and the delivery mechanism. The controller is structured to interpret, via a pump diagnostic circuit, first and second pump parameters indicative of first and second pump rates, interpret, via a dosing diagnostic circuit, first and second dosing parameters indicative of at least one of (i) first and second reductant flows or (ii) first and second injector characteristics, determine, via a delivery diagnostic circuit, a delivery status based, at least in part, on the interpretation of the first and second pump parameters and the first and second dosing parameters, and generate, via the delivery diagnostic circuit, a status command indicative at least one of an under-restricted delivery mechanism or an over-restricted delivery mechanism in response to the determination of the delivery status.

In a selective catalytic reductant dosing system including a reductant injector adapted to inject liquid reductant into an exhaust line, a method of analyzing flow of reductant through the injector includes determining a measure of the temperature of the injector prior to activation of the injector. The method also includes activating the injector and determining a measure of the temperature of the injector subsequent to activation of the injector. The method also includes analyzing the flow of reductant through the injector consequential to the activation by analyzing changes in the measure of temperature of the injector prior to activation and the measure of temperature of the injector subsequent to activation.

A method for controlling an SCR system having two metering valves and a feed pump, wherein the two metering valves are operated in such a way that a reducing agent solution is metered in simultaneously via the two metering valves, at least over part of a metering time period (t.sub.Dos).

Disclosed is a method for adapting control of a reducing agent dosing unit in a reducing agent provision system for emission control of a combustion engine. Characteristics relating to pressure variations associated with a dosing cycle are used for determining a first time period and a second time period. The time periods relate to a delay between activation of dosing and de-activation of dosing, respectively. The first time period and second time period are used for adapting operation of said reducing agent dosing unit.

An exhaust purification system includes: an NOx reduction type catalyst; an MAF sensor; an SOx purge control unit that uses an air system control having an intake air amount feedback-controlled based on a target intake air amount and an injection system control for a target injection increase amount set based on the target intake air amount, and a fuel injection amount feedback-controlled based on the target injection increase amount; an SOx purge prohibition processing unit that prohibits an SOx purge control; and a warming mode control unit that open-loop controls an air system when the SOx purge control is prohibited, controls the fuel injection amount, and maintains the exhaust gas at a temperature. The SOx purge control unit executes the injection system control by switching the target intake air amount into an actual intake air amount when starting the SOx purge control after a warming mode control is ended.

A method for detecting a dosing error of a reduction agent in a dosing module of an SCR catalytic converter system. The SCR catalytic converter system comprises the dosing module, which has a dosing valve and a flow valve as well as a delivery module with delivery pump. The SCR catalytic converter system, furthermore, has a return, in which a further flow valve is arranged. Said flow valve changes an effective cross-sectional area of the return. The method herein comprises the following steps: at the beginning, the dosing valve is closed (200). At a first pressure value (p.sub.1) in the system the delivery pump is switched off (201) and a measurement (202) of a first pressure rate (.sub.RL.sup.dynamic) of the flow valve of the return subsequently takes place. Additional operation of the pump and the dosing valve occurs and a ratio of pressure rates is determined.

A heat shield for a reductant delivery unit (RDU), the RDU including a fluid injector with a fluid inlet and a fluid outlet, and a clamp flange for attachment to a mounting boss of a vehicle exhaust pipe. The heat shield includes a first portion which is attached to the fluid injector so as to at least partly cover the fluid outlet thereof. The first portion serves as a thermal barrier for the fluid injector and a mechanical barrier for preventing particles in the vehicle exhaust pipe from contacting the fluid injector when the RDU is attached to the vehicle exhaust pipe. The heat shield further includes a second portion which extends radially outwardly from the first portion for sealing the attachment between the clamp flange and the mounting boss of the vehicle exhaust pipe when the RDU is attached thereto.

An exhaust purification system is provided with a NOx-occlusion-reduction-type catalyst and a NOx purge rich control unit that executes NOx purge of reducing and purifying the occluded NOx by putting the exhaust into a rich state by fuel injection control, in a case where a catalyst temperature of the NOx-occlusion-reduction-type catalyst is equal to or higher than a catalyst temperature threshold value and a NOx occlusion amount of the NOx-occlusion-reduction-type catalyst is equal to or higher than an NOx occlusion amount threshold value, and executes the NOx purge even when the NOx occlusion amount is less than the NOx occlusion amount threshold value, in a case where the catalyst temperature is equal to or higher than a catalyst temperature threshold value which is greater than the catalyst temperature threshold value.

An automotive exhaust aftertreatment system for reducing effluents, such as nitrous oxides (NOx), in exhaust gasses passing through the system. The automotive exhaust aftertreatment system includes a dosing unit configured to inject primary and secondary reductant fluids into exhaust gasses based on various strategies to optimize operation of the system.