Compact exhaust gas treatment unit with reaction agent addition and motor vehicle having an exhaust gas treatment unit

1. An exhaust gas treatment unit, comprising:

an approach flow region, a diverting region, a backflow region and an outflow region disposed in series in terms of flow;

said approach flow region having an outer surface on which said backflow region and said outflow region are disposed; and

an addition unit disposed in said outflow region and configured to add a reaction agent, said addition unit being disposed to feed the reaction agent at least partially onto said outer surface of said approach flow region, said addition unit being disposed radially to an outside of said approach flow region and aligned toward said approach flow region.

2. The exhaust gas treatment unit according to claim 1 , wherein said outer surface is configured to be heated at least in part.

3. The exhaust gas treatment unit according to claim 1 , which further comprises an exhaust gas flow direction, at least said backflow region having a flow cross section changing transversely to said exhaust gas flow direction.

4. The exhaust gas treatment unit according to claim 1 , wherein said outer surface of said approach flow region has a surface area and at least one at least partial coating or a structure configured to increase said surface area of said outer surface relative to a surface without said at least one partial coating or structure.

5. The exhaust gas treatment unit according to claim 1 , wherein said approach flow region has at least one heat transfer element configured to transfer heat in the exhaust gas to said outer surface.

6. The exhaust gas treatment unit according to claim 1 , wherein said backflow region has at least one flow deflector configured to deflect or laminarize the exhaust gas.

7. The exhaust gas treatment unit according to claim 1 , which further comprises:

an oxidation catalytic converter disposed within a region of said approach flow region;

said backflow region surrounding said approach flow region in said region having said oxidation catalytic converter;

said diverting region configured to divert and pass an exhaust gas through said backflow region into said outflow region;

said approach flow region having an upstream inflow region extending in the form of a tube through said outflow region to said outer surface; and

said addition unit configured to apply a reducing agent or a reducing agent precursor to said outer surface.

8. A motor vehicle, comprising:

an internal combustion engine;

an exhaust line configured to receive exhaust gas from said internal combustion engine, said exhaust line having at least one exhaust gas treatment unit according to claim 1 ; and

a device configured to supply a reaction agent to said at least one exhaust gas treatment unit.

9. The exhaust gas treatment unit according to claim 1 , wherein said outer surface of said approach flow region has a coating with a hydrolysis function.

10. An exhaust gas treatment unit, comprising:

a housing;

said housing containing an approach flow region, a diverting region, a backflow region and an outflow region disposed in series in terms of flow, said outflow region being a region where exhaust gas exits said housing;

said approach flow region having an outer surface on which said backflow region and said outflow region are disposed; and

an addition unit disposed in said outflow region and configured to add a reaction agent, said addition unit being disposed to feed the reaction agent at least partially onto said outer surface of said approach flow region, said addition unit being disposed radially to an outside of said approach flow region and aligned toward said approach flow region.