Method for regulating an ionization device in an exhaust-gas aftertreatment apparatus and motor vehicle in which the method is carried out

1. A method for regulating an ionization device in an exhaust-gas aftertreatment apparatus of an internal combustion engine, the method comprising the following steps:

providing at least one cathode at a distance from an anode in the exhaust-gas aftertreatment apparatus;

applying a high voltage between the at least one cathode and the anode;

predefining a first value for the high voltage;

detecting a current, generated by the high voltage, between the at least one cathode and the anode; and

predefining a second value, being lower than the predefinable first value, for the high voltage if the detected current exceeds a predefinable first current intensity for a predefinable number of times.

2. The method according to claim 1 , which further comprises increasing the predefinable first value for the high voltage with a predefinable high-voltage increase rate.

3. The method according to claim 1 , which further comprises the following steps:

determining a current increase rate of the detected current; and

predefining the second value for the high voltage if the current increase rate exceeds a predefinable current increase value.

4. The method according to claim 3 , wherein the predefinable first value for the high voltage assigned to the current in the event of exceeding the predefinable current increase value is a critical high voltage, and the predefinable second value for the high voltage is less than or equal to the critical high voltage.

5. The method according to claim 1 , which further comprises reducing the predefined high voltage to the predefinable second value if at least one of the following takes place:

the current exceeds the predefinable first current intensity or

a current increase rate exceeds a current increase value, multiple times.

6. The method according to claim 1 , which further comprises predefining the second value in such a way that a current with a predefinable second current intensity flows.

7. The method according to claim 1 , which further comprises predefining at least one of the first value or the second value as a function of at least one of the following parameters:

aging of the cathode,

operating point of the internal combustion engine,

exhaust-gas mass flow rate,

exhaust gas humidity,

exhaust gas temperature,

load of the internal combustion engine, or

size of particles in the exhaust gas.

8. The method according to claim 1 , which further comprises predefining the first value as a function of the second value from at least one previous operating cycle.

9. The method according to claim 1 , which further comprises generating the high voltage between the at least one cathode and the anode using a high-voltage source, adjusting a magnitude of the high voltage to be proportional to a low voltage applied to an input side of the high-voltage source and controlling the magnitude of the high voltage by using the low voltage.

10. The method according to claim 1 , which further comprises generating the high voltage between the at least one cathode and the anode by using a high-voltage source, and controlling a magnitude of the high voltage by using a frequency of a control voltage applied to the high-voltage source.

11. The method according to claim 1 , which further comprises applying as high a voltage as possible to the ionization device at all times and at least one of preventing formation of an arc or extinguishing an already formed arc in the ionization device.

12. A motor vehicle, comprising:

an internal combustion engine;

an exhaust-gas aftertreatment apparatus having an ionization device with a cathode and an anode disposed at a distance from each other; and

a controller configured to regulate said ionization device by:

applying a high voltage between said cathode and said anode;

predefining a first value for the high voltage;

detecting a current, generated by the high voltage, between said cathode and said anode; and

predefining a second value, being lower than the predefinable first value, for the high voltage if the detected current exceeds a predefinable first current intensity for a predefinable number of times.

13. The motor vehicle according to claim 12 , wherein said controller regulates said ionization device by applying as high a voltage as possible to said ionization device at all times and at least one of prevents formation of an arc or extinguishes an already formed arc in said ionization device.