Metering arrangement for a liquid exhaust-gas aftertreatment medium and metering method

摘要

A metering arrangement (3, 30) is proposed for a liquid exhaust-gas aftertreatment medium for the aftertreatment of the exhaust gas of an internal combustion engine which has an exhaust-gas system, in particular for a urea/water solution, having a delivery pump (7) and a metering module (13), wherein the delivery pump (7) is connected to a suction line (23) for sucking the exhaust-gas aftertreatment medium out of a tank (1), wherein the delivery pump (7) and the metering module (13) are connected to one another via a pressure line (25), and the exhaust-gas aftertreatment medium can be fed via the metering module (13) to the exhaust-gas system, wherein a recirculation pump (8) is arranged parallel to the delivery pump (7), wherein the recirculation pump (8) is connected on the suction side to the metering module (13). Furthermore, a corresponding method for metering is proposed.

主权项

1. A metering arrangement (3, 30) for a liquid exhaust-gas aftertreatment medium for the aftertreament of exhaust gas of an internal combustion engine having an exhaust gas system, the metering arrangement comprising: a feed pump (7) and a metering module (13), wherein the feed pump (7) is connected to a suction line (23) for sucking the exhaust-gas aftertreatment medium out of a tank (1), wherein the feed pump (7) and the metering module (13) are connected to one another via a pressure line (25), and the exhaust-gas aftertreatment medium can be fed to the exhaust gas system via the metering module (13), further comprising a recirculation pump (8), which is connected on a suction side to the metering module (13), wherein the pressure line (25) is connected, between the feed pump (7) and the metering module (13), to a return line (27) which opens directly into the tank or above a maximum filling level of the tank, wherein the return line (27) has at least one of a restrictor (15) or a nonreturn valve (17) which opens toward the tank (1), wherein exhaust-gas aftertreatment medium, which is fed by the recirculation pump (8), can be recirculated to the tank via the return line, and wherein at least one of the feed pump (7) or the recirculation pump (8) is embodied as a diaphragm pump.