Device for introducing an additive into an exhaust gas

Abstract

A reducing agent or an additive that releases an agent is often added to an exhaust gas from engines in order to chemically convert constituents, in particular nitrogen oxides, in the exhaust gas. To achieve intimate mixing of the exhaust gas with the reducing agent or additive over a short section of the gas duct, at least one mixer and at least one nozzle for introducing the additive into the exhaust gas are structurally and functionally combined with one another.

We claim:  
     
         1 . A device for introducing an additive into an exhaust gas, the exhaust gas being introduced into an exhaust gas line from a diesel engine and having a flow direction, the device comprising: 
 at least one nozzle; and    at least one mixer for mixing the exhaust gas with the additive, said mixer and said nozzle combined with one another to form a structural and functional unit, said mixer having a tubular body disposed approximately parallel in terms of the flow direction of the exhaust gas and housing said nozzle, said tubular body having an upstream end with a first opening formed therein and a downstream end with a second opening formed therein and communicating with said first opening, said mixer having lamellae supported by said tubular body, and said lamellae, with regard to the flow direction of the exhaust gas, face upstream at said upstream end of said tubular body and face downstream at said downstream end of said tubular body.    
     
     
         2 . The device according to  claim 1 , wherein said tubular body has a cross section that is circular.  
     
     
         3 . The device according to  claim 1 , wherein said tubular body has a diameter in a range of 0.2 to 0.5 times a diameter of the exhaust gas line.  
     
     
         4 . The device according to  claim 1 , wherein said tubular body has a length that is approximately 0.2 to 0.5 times a diameter of the exhaust gas line.  
     
     
         5 . The device according to  claim 1 , wherein said mixer has a tubular connection piece projecting into the exhaust gas line and guided onto said tubular body, said mixer further having a tube serving as a feed line and as a support for said nozzle, said tube extending into said tubular body through said tubular connecting piece.  
     
     
         6 . The device according to  claim 1 , wherein mixer has a center axis and said nozzle lies on said center axis in such a manner that the additive can be sprayed in the flow direction of the exhaust gas.  
     
     
         7 . The device according to  claim 1 , wherein said tubular body has an axis, and said lamellae supported by said upstream end and said downstream end of said tubular body form an angle of 30° to 60°, with said axis of said tubular body and, said lamellae for support, have free ends directed onto an inner side of the exhaust gas line.  
     
     
         8 . The device according to  claim 1 , wherein said lamellae have root ends connected to said tubular body and free ends being approximately twice as wide as said root ends.  
     
     
         9 . The device according to  claim 1 , wherein said lamellae have a given width, and between adjacent ones of said lamellae free spaces are formed having a width approximately as wide as said given width of said lamellae.  
     
     
         10 . The device according to  claim 1 , wherein said lamellae that face upstream are disposed staggered with respect to said lamellae that face downstream.  
     
     
         11 . The device according to  claim 1 , wherein a number of said lamellae facing upstream is equal to a number of said lamellae facing downstream.  
     
     
         12 . The device according to  claim 1 , wherein said tubular body bears a same number of said lamellae at both of said upstream end and said downstream end.  
     
     
         13 . The device according to  claim 1 , wherein said lamellae include planar metal sheets.  
     
     
         14 . The device according to  claim 12 , wherein said tubular body bears between four and eight of said lamellae at both of said upstream end and said downstream end.  
     
     
         15 . The device according to  claim 7 , wherein said angle is 45°.