Method and Apparatus for Operating a Linear Lambda Probe

摘要

A signal from a linear lambda probe, which signal is meant to represent an air/fuel ratio for the gas flowing in the exhaust section, specifically prior to combustion of said gas, is determined based on a pump current. A difference signal is formed based on a difference between a pump voltage signal and a Nernst voltage signal. An offset error in the measured signal is determined based on the difference signal for an approximately stoichiometrically prescribed raw setpoint value for the air/fuel ratio, with a setpoint value for the air/fuel ratio being determined based on the raw setpoint value and a forced excitation signal.

主权项

1. A method for operating a linear lambda probe arranged in an exhaust section of an internal combustion engine, the linear lambda probe comprising a first electrode arranged on the exhaust gas side, a second electrode and a third electrode arranged adjacent to a measurement chamber, and a fourth electrode arranged adjacent to a reference air volume, wherein solid electrolytes are respectively situated between the first and second electrodes and between the third and fourth electrodes and a diffusion barrier is formed between a free volume of the measurement chamber and the exhaust section, wherein a potential difference between the first and second electrodes forms a pump voltage signal and a potential difference between the fourth and third electrodes forms a Nernst voltage signal, the method comprising:
determining a measurement signal of the linear lambda probe based on a pump current applied between the first and second electrodes, the measurement signal representing an air/fuel ratio of gas flowing in the exhaust section, prior to combustion of said gas, generating a difference signal based on a difference between the pump voltage signal and the Nernst voltage signal, determining a setpoint value of the air/fuel ratio based on a raw setpoint value of the air/fuel ratio and a forced excitation signal, determining whether the raw setpoint value of the air/fuel ratio is approximately stoichiometrically predefined, and in response to determining that the raw setpoint value of the air/fuel ratio is approximately stoichiometrically predefined, determining an offset error of the measurement signal based on the difference signal.