Method for operating an exhaust-gas system with lambda control and motor vehicle having the system

1. A method for operating an internal combustion engine exhaust system having at least one particle separator and a catalytic converter, the method comprising the following steps:

providing the internal combustion engine as a spark-ignition engine;

providing the catalytic converter as a three-way catalytic converter and disposing the at least one particle separator upstream of the three-way catalytic converter in a flow direction of the exhaust system;

a) carrying out processes in the internal combustion engine with a lambda control about a control value;

b) identifying a regeneration process of the at least one particle separator;

c) determining a required oxygen demand for the regeneration process of the at least one particle separator by determining the required oxygen demand as an amount of oxygen required in the exhaust gas solely for the oxidation of particles in the at least one particle separator; and

d) adapting the lambda control to a lambda value in a range of from 1.02 to 1.05 for providing sufficient oxygen for the determined oxygen demand during a period of the regeneration process of the at least one particle separator such that more air is supplied than in the lambda control in step a) in order to add only precisely the required oxygen demand to the exhaust gas.

2. The method according to claim 1 , which further comprises providing the control value in step a) as a lambda value of 1.0.

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

varying the control value in step a) about a lambda value of 1.0 with a first amplitude; and

setting a second amplitude in step d) being greater than the first amplitude.

4. The method according to claim 1 , which further comprises calculating the determination of the oxygen demand based on a regeneration model of the at least one particle separator.

5. The method according to claim 1 , wherein a temperature of at least 500° C. is present in vicinity of the at least one particle separator during step d).

6. A motor vehicle, comprising:

a spark-ignition engine;

an exhaust system connected to said spark-ignition engine for conducting a flow of exhaust gas produced in said spark- ignition engine through said exhaust system in a flow direction;

at least one sensor disposed in said exhaust system;

at least one particle separator and a three-way catalytic converter disposed in series in said flow direction in said exhaust system and said at least one particle separator being disposed upstream of said three-way catalytic converter with respect to said flow direction; and

an electronic controller interacting with said at least one sensor, and said electronic controller configured to:

a) carry out processes in said spark-ignition engine with a lambda control about a control value;

b) identify a regeneration process of said at least one particle separator;

c) determine a required oxygen demand for the regeneration process of said at least one particle separator by determining the required oxygen demand as an amount of oxygen required in the exhaust gas solely for the oxidation of particles in said at least one particle separator; and

d) adapt the lambda control to a lambda value in a range of from 1.02 to 1.05 to provide oxygen sufficient oxygen for the determined oxygen demand during a period of the regeneration process of the at least one particle separator such that more air is supplied than in the lambda control in step a) in order to add only precisely the required oxygen demand to the exhaust gas.

7. The motor vehicle according to claim 6 , which further comprises a first lambda probe disposed upstream of said at least one particle separator and at least one second lambda probe disposed downstream of said at least one particle separator or downstream of said three-way catalytic converter, in said flow direction.

8. The motor vehicle according to claim 6 , wherein said at least one particle separator includes a honeycomb body having a metallic foil and a wire nonwoven delimiting open channels.

9. The motor vehicle according to claim 7 , wherein said at least one particle separator includes a honeycomb body having a metallic foil and a wire nonwoven delimiting open channels.