Catalytic heater for an exhaust gas system of an internal combustion engine, exhaust gas system and method of operating an exhaust gas system

1 . An exhaust gas system for an internal combustion engine, the exhaust gas system comprising:

at least one exhaust gas treatment assembly;

a catalytic heater arranged downstream of said at least one exhaust gas treatment assembly with regard to an exhaust gas flow direction; said catalytic heater including:

at least one electrically excitable heating element;

a hydrocarbon release arrangement for releasing liquid hydrocarbon toward said at least one electrically excitable heating element; and,

an oxidation catalyst arrangement for oxidizing the hydrocarbon heated at said at least one electrically excitable heating element;

wherein said catalytic heater is disposed in an exhaust gas system section to be positioned to run at least downward in a height direction away from an internal combustion engine.

2 . The exhaust gas system of claim 1 , wherein said oxidation catalyst arrangement comprises an oxidation catalyst block disposed on an outflow side of said at least one electrically excitable heating element for uptake and oxidation of hydrocarbon evaporated at said at least one electrically excitable heating element.

3 . The exhaust gas system of claim 1 , wherein said oxidation catalyst arrangement comprises an oxidation catalyst material coating of said at least one electrically excitable heating element.

4 . The exhaust gas system of claim 1 , wherein said at least one exhaust gas treatment assembly comprises a first exhaust gas treatment assembly having at least one of the following: i) an oxidation catalyst; and, ii) a particulate filter.

5 . The exhaust gas system of claim 1 , wherein said at least one exhaust gas treatment assembly comprises a second exhaust gas treatment assembly having an SCR catalyst.

6 . The exhaust gas system of claim 5 , wherein said first exhaust gas treatment assembly is disposed upstream with respect to said second exhaust gas treatment assembly in the exhaust gas flow direction.

7 . The exhaust gas system of claim 1 , wherein said catalytic heater is disposed downstream of at least one of the following: i) an exhaust gas turbocharger; and, ii) a third exhaust gas treatment assembly in the exhaust gas flow direction.

8 . The exhaust gas system of claim 7 , wherein said third exhaust gas treatment assembly comprises an SCR catalyst.

9 . The exhaust gas system of claim 1 , further comprising: an electively blockable bypass flow pathway arranged parallel to said catalytic heater.

10 . The exhaust gas system of claim 9 , wherein the electively blockable bypass flow pathway only bypasses the catalytic heater.

11 . The exhaust gas system of claim 1 , wherein

the exhaust gas system section in which the catalytic heater is disposed to be positioned to run at least downward in the height direction and to run laterally away from the internal combustion engine.

12 . The exhaust gas system of claim 1 , wherein the hydrocarbon release arrangement is positioned in an arc region of an exhaust gas guiding component positioned upstream of the heating element.

13 . A method of operating an exhaust gas system including: at least one exhaust gas treatment assembly; a catalytic heater arranged downstream of said at least one exhaust gas treatment assembly with regard to an exhaust gas flow direction; said catalytic heater including: at least one electrically excitable heating element; a hydrocarbon release arrangement for releasing liquid hydrocarbon toward said at least one electrically excitable heating element; and, an oxidation catalyst arrangement for oxidizing the hydrocarbon heated at said at least one electrically excitable heating element; the method comprising the step of:

operating the at least one electrically excitable heating element of the catalytic heater such that liquid hydrocarbon meets a surface of the at least one electrically excitable heating element and is heated and is oxidized over the oxidation catalyst arrangement to generate heat,

wherein the excitation of the at least one electrically excitable heating element is started before startup of an internal combustion engine,

wherein the injection of hydrocarbon onto the at least one electrically excitable heating element is commenced before startup of the internal combustion engine, wherein:

a) before startup of the internal combustion engine, in a preinjection operation, hydrocarbon is injected in at least one of the following ways: i) in a predetermined amount; and, ii) for a predetermined period of time;

b) after the preinjection operation has ended, the internal combustion engine is driven to rotate without ignition; and,

c) before startup of the internal combustion engine, in a last preinjection operation, hydrocarbon is injected in at least one of a following ways: i) in a predetermined amount; and, ii) for a predetermined period of time.

14 . The method of claim 13 , wherein the injection of hydrocarbon toward the at least one electrically excitable heating element is started when at least one of the following applies:

i) after commencement of the excitation of the at least one electrically excitable heating element, the oxidation catalyst arrangement has a predetermined temperature that permits catalytic oxidation of hydrocarbon over the oxidation catalyst arrangement; and,

ii) after a predetermined period of time has passed since commencement of the excitation of the at least one electrically excitable heating element.

15 . The method of claim 13 , wherein the performance of measure c) is preceded by at least one repetition of measures a) and b) or, after or during the performance of measure c), the internal combustion engine is put into operation.

16 . The method of claim 15 , wherein:

the injection of hydrocarbon is ended with the ending of measure c); or,

the injection of hydrocarbon is restarted or continued after measure c) has ended and after the internal combustion engine has been started up.

17 . The method of claim 13 , wherein, after the internal combustion engine has been started up, the hydrocarbon injection rate is determined depending on at least one of the following: i) a temperature of the oxidation catalyst arrangement; and, ii) an exhaust gas volume flow rate in the exhaust gas system.

18 . The method of claim 17 , wherein at least one of the following applies:

i) the hydrocarbon injection rate increases with increasing temperature of the oxidation catalyst arrangement; and,

ii) the hydrocarbon injection rate decreases with increasing exhaust gas volume flow rate.

19 . A method of operating an exhaust gas system including: at least one exhaust gas treatment assembly; a catalytic heater arranged downstream of said at least one exhaust gas treatment assembly with regard to an exhaust gas flow direction; said catalytic heater including: at least one electrically excitable heating element; a hydrocarbon release arrangement for releasing liquid hydrocarbon toward said at least one electrically excitable heating element; and, an oxidation catalyst arrangement for oxidizing the hydrocarbon heated at said at least one electrically excitable heating element; the method comprising the step of:

operating the at least one electrically excitable heating element of the catalytic heater such that liquid hydrocarbon meets a surface of the at least one electrically excitable heating element and is heated and is oxidized over the oxidation catalyst arrangement to generate heat,

wherein, after the internal combustion engine has been started up, the hydrocarbon injection rate is determined depending on at least one of the following: i) a temperature of the oxidation catalyst arrangement; and, ii) an exhaust gas volume flow rate in the exhaust gas system,

wherein at least one of the following applies:

i) the hydrocarbon injection rate increases with increasing temperature of the oxidation catalyst arrangement; and,

ii) the hydrocarbon injection rate decreases with increasing exhaust gas volume flow rate.

20 . The method of claim 19 , wherein the excitation of the at least one electrically excitable heating element is started before startup of an internal combustion engine.

21 . The method of claim 20 , wherein the injection of hydrocarbon onto the at least one electrically excitable heating element is commenced with or after startup of the internal combustion engine.