Apparatus and method for lambda control of spark-ignition engines, and motor vehicle

A device for lambda control of a gasoline engine, the device comprising:

• a first three-way catalytic converter,
• a second three-way catalytic converter,
• a linear lambda sensor,
• a binary lambda sensor, wherein the binary lambda sensor is a jump sensor configured to measure two states rich and lean without being configured to measure an exact lambda value or oxygen content in an exhaust gas, and
• an NOx sensor,
• wherein the first three-way catalytic converter is arranged upstream of the second three-way catalytic converter,
• wherein the linear lambda sensor is arranged upstream of the first three-way catalytic converter,
• wherein the binary lambda sensor is arranged downstream of the first three-way catalytic converter and upstream of the second three-way catalytic converter, or
• wherein the binary lambda sensor is arranged in the first three-way catalytic converter or in the second three-way catalytic converter,
• wherein the NOx sensor is arranged downstream of the second three-way catalytic converter and
• wherein the linear lambda sensor, the binary lambda sensor and the NOx sensor are connected to a control device for lambda control
• wherein
• the control device has a cascade control with a first controller, a second controller and a third controller,
• wherein the first controller is set up for mixture control using a setpoint value of the linear lambda sensor,
• wherein the second controller is set up for trim control of the setpoint value of the linear lambda sensor using a setpoint value of the binary lambda sensor, and
• wherein the third controller is set up for trim control of the setpoint value of the binary lambda sensor using at least one setpoint value and/or using at least one measured value of the NOx sensor,
• wherein the third controller has a measured value of the NOx sensor as an input value and a trim value of the second controller as an output value,
• the second controller has a measured value of the binary lambda sensor and the trim value of the second controller as input values and a trim value of the first controller as an output value, and
• the first controller has a measured value of the linear lambda sensor and the trim value of the first controller as input values and a fuel quantity to be injected as output value and
• wherein the trim value of the second controller is offset against the setpoint value of the second controller to form a corrected setpoint value of the second controller and
• wherein the trim value of the first controller is offset against the setpoint value of the first controller to form a corrected setpoint value of the first controller.