Patent ID: 6959539

Claim:
An exhaust-gas cleaning system for an internal-combustion engine having an exhaust-gas stream, comprising: an engine management system for setting a composition of a mixture in the internal-combustion engine; a first exhaust-gas sensor for measuring a composition of the exhaust-gas stream of the internal-combustion engine, said first exhaust-gas sensor configured in the exhaust-gas stream of the internal-combustion engine; a first exhaust-gas cleaning element configured in the exhaust-gas stream of the internal-combustion engine, said first exhaust-gas cleaning element configured downstream from said first exhaust-gas sensor; a control unit for controlling the composition of the mixture in the internal-combustion engine as a function of the composition of the exhaust-gas stream measured by said first exhaust-gas sensor, said control unit having an input connected to said first exhaust-gas sensor, said control unit having an output connected to said engine management system, and said control unit having two I-controllers connected in series, each one of said two I-controllers having a control response; and a second exhaust-gas sensor configured in the exhaust-gas stream of the internal-combustion engine, said second exhaust-gas sensor configured downstream from said first exhaust-gas cleaning element, said second exhaust-gas sensor measuring the exhaust-gas composition of the exhaust-gas stream of the internal-combustion engine, and said second exhaust-gas sensor being connected to one of said two I-controllers to influence the control response of said one of said two I-controllers as a function of the exhaust-gas composition measured by said second exhaust-gas sensor; said control unit having a control response and a control input for influencing the control response to modify a local balance of an oxygen concentration in said first exhaust-gas cleaning element; and said control input of said control unit being connected to said second exhaust-gas sensor.