Exhaust gas subsequent processing method and method therefor

Abstract

The invention relates to a method and device for subsequently treating exhaust gases of an internal combustion engine while using a reactant, particularly a reducing agent, which is to be introduced into the exhaust gases. According to the invention, the reactant is pumped by means of a delivery device (4), particularly a pump, out of a reactant reservoir (1) and to a dosing device (80), particularly a dosing valve so that after the dosing device is opened, the reactant can be introduced into an exhaust gas line of the internal combustion engine in a dosed manner (dosing operation). Reactant can be conveyed back from the delivery device (4) to the reactant reservoir (1) via a return line (12). The reactant can circulate between the delivery device (4) and the reactant reservoir (1) whereby, particularly when the dosing device is closed, preventing the reactant from freezing (freezing prevention).

Description

technical field [0001] The invention relates to a method and a device for exhaust gas aftertreatment of an internal combustion engine of the type according to the independent claims. Background technique [0002] It has been known from DE 199 46 902 A1 to introduce an aqueous urea solution for nitrogen removal into the exhaust gas line behind the engine and to provide a return line from the delivery pump back to the urea container, which return line Used to reduce possible overpressure in the urea line or for venting the urea line, but especially in the critical case of freezing, especially outside the time of metering the reducing agent into the vent line , no continuous heat exchange is provided between the aqueous urea solution and the parts of the exhaust gas aftertreatment device at risk of freezing. [0003] Furthermore, DE 102 54 981 A1 discloses removing reducing agent remaining in the reducing agent-carrying line after metering by means of compressed air. Content...

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Problems solved by technology

[0002] It has been known from DE 199 46 902 A1 to introduce an aqueous urea solution for nitrogen removal into the exhaust gas line behind the engine and to provide a return line from the delivery pump back to the urea container, which return line Used to reduce possible overpressure in the urea line or for venting the urea line, but especially in the critical case of freezing, especially outside the time of metering the reducing agent into the vent line , there is no continuous heat exchange between the aqueous urea solution and the parts of the exhaust aftertreatment device that are at risk of freezing

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