Pipe evaporator for feeding additional fuel into the exhaust gas

A device for re-treating exhaust gases of an internal combustion engine with a reducing catalytic converter (11) which serves to reduce NO.sub.x ingredients in the exhaust gases, in which an exhaust pipe (9) leads to the catalytic converter, an electrically controlled valve (23) is provided as a device for metering a reducing agent to be introduced into the stream of exhaust gas supplied to the catalytic converter (11), an evaporator device (26) is provided to evaporate the metered reducing agent before being introduced into the exhaust gas, the evaporator device (26) has a hollow body (41) which protrudes through a wall of the exhaust pipe (9) into the exhaust stream and communicates with the exhaust stream through at least one flow opening (43), a heating body (40) protrudes into an interior (44) of the hollow body, the heating body is spaced slightly apart from the inner wall of the hollow body, by which a reducing agent introduced into the remaining interior by the heating body is heated to a temperature of evaporation, and the hollow body (41) is a metal sheath, which for communication of its interior with the exhaust stream has a flow opening (43) on a face end.