Patent ID: 6848251

Claim:
In a device for generating a mixture of reducing agent and air for catalytically removing nitrogen from exhaust gases of internal combustion engines, having a mixing space ( 16 ) into which reducing agent can be introduced via a reducing agent delivery conduit ( 64 , 164 ) and air can be introduced via an air delivery conduit ( 61 , 165 ), the improvement comprising means ( 20 , 21 , 22 , 23 , 24 , 60 , 61 , 165 ) for pressurizing the air whereby the air that acts on the reducing agent is carried with a supercritical pressure difference through the air delivery conduit, and the air quantity flowing into the mixing chamber can be kept constant in certain pressure regions, independently of a pressure prevailing in the mixing space, the mixing space being embodied as a space separate from the arrangement carrying the exhaust gases, and the mixture of reducing agent and air can be transported from the mixing chamber to a catalytic converter ( 30 ) via a line ( 25 ) communicating with the mixing space, the reducing agent delivery conduit ( 64 , 164 ) being embodied as a nozzle ( 63 ) disposed in a mixing chamber housing bore ( 62 ), and the air delivery conduit being embodied as an annular gap ( 61 ), concentrically surrounding the nozzle ( 63 ), between the nozzle and the wall ( 62 a ) of the mixing chamber housing bore ( 62 ), and an end portion ( 61 a ) of the annular gap ( 61 ), which portion discharges into the mixing space ( 16 ), being embodied as widening in the flow direction of the air.