Vorrichtung und Verfahren zur Dosierung eines Reduktionsmittels

摘要

A device for metering a reducing agent, in particular a urea or aqueous urea solution, used in the field of catalytic waste gas treatment comprises a tank (1) for storing said reducing agent, a pump (4) for supplying said reducing agent from the tank to an injection valve (7), via which said reducing agent can be delivered to a mixing chamber. Tank (1), pump (4) and injection valve (7) are connected to each other by a connection system comprising a first line (1a) between tank and pump and a second line (1b) between pump and injection valve, whereby a controllable ventilation circuit (1d, 10, 1c) returning to the tank (1) is branched off from the second line (1b).