Patent ID: 7866144

Claim:
An arrangement for the dosed injection of a reducing medium, into an exhaust tract ( 2 ) of an internal combustion engine, comprising: a pump ( 1 ) for the pulsed pumping of the reducing medium, an injection nozzle ( 5 ) arranged in the exhaust tract ( 2 ) and disposed in communication with the pump ( 1 ) for injecting the reducing medium into the exhaust tract, the injection nozzle ( 5 ) including a valve element ( 33 ) which automatically opens and closes the injection nozzle ( 5 ) depending on the pressure generated by the pump ( 1 ) periodically and which permits injection of the reducing medium into the exhaust tract ( 2 ) only when the pressure of the reducing medium is in excess of a certain value so that atomization of the reducing medium takes place only when the reducing medium is pressurized to a degree exceeding the certain pressure, the pump ( 1 ) including an operating chamber ( 26 ) which is in communication with a storage container ( 8 ) via a suction line ( 43 ) and a check valve ( 23 ) and with the injection nozzle ( 5 ) via a high pressure line ( 4 ) and a check valve ( 25 ), a pressure relief line ( 41 ) extending between the high pressure line ( 4 ) downstream of the check valve ( 25 ) and a pressure relief arrangement ( 42 ) which is in communication with the pump operating chamber ( 26 ), the pressure relief arrangement ( 42 ) providing, during the suction stroke of the pump ( 1 ), for a displacement of a volume from the high pressure line ( 4 ) toward the pump operating chamber ( 26 ) for rapidly reducing the pressure in the high pressure line ( 4 ) and the injection nozzle ( 5 ).