Method for self-balancing of a lambda sensor and exhaust gas system

An exhaust gas system (10) for a motor vehicle propelled by an internal combustion engine, comprising:

• a first lambda sensor (18) for detecting a first lambda value of a first motor bank (14) of an internal combustion engine (12),
• a second lambda sensor (20) for detecting a second lambda value of a second motor bank (16) of the internal combustion engine (12),
• a motor bank control system for adjusting the first motor bank (14) and the second motor bank (16) such that substantially equal lambda values are achieved for the first motor bank (14) and for the second motor bank (16),
• wherein the first and second lambda sensors (18, 20) comprise first and second self-balancing adjusters configured to:
• measure a pumping current (Ip) of the lambda sensors for detecting a lambda value (λ);
• measure a pumping voltage (Up) of the lambda sensors correlating to the pumping current (Ip);
• check whether the measured pumping current (Ip) and the measured pumping voltage (Up) lie within a specified tolerance range (33) of a characteristic curve specification for a dependence between the pumping current (Ip) and the pumping voltage (Up);
• and
• when the values lie outside the tolerance range (33) of the characteristic curve specification, then adjusting the lambda value (λ) based on the pumping voltage (Up) of the lambda sensor rather than based on the pumping current (Ip) of the lambda sensor, and, in an adjusted state, measuring a further pumping current (Ip) of the lambda sensor and, for the self-alignment of the lambda sensor, the pumping current offset (32) is derived from at least one of:
• a further pumping current (Up) for a compensation of a leakage current, a fault current of the lambda sensor and a cable harness belonging to the lambda sensor.

An exhaust gas system (10) for a motor vehicle propelled by an internal combustion engine, comprising

• an exhaust gas catalyst (24) for chemically converting combustion pollutants of an internal combustion engine (12);
• a pre-catalyst broadband lambda sensor (26) provided on an input side of the exhaust gas catalyst (24);
• and
• a catalyst lambda sensor (28) provided on the output side of the exhaust gas catalyst (24),
• wherein the pre-catalyst broadband lambda sensor (26) comprises a self-alignment adjuster configured to:
• measure a pumping current (Ip) of the lambda sensors provided for detecting a lambda value (λ);
• measure a pumping voltage (Up) of the lambda sensor correlating to the pumping current (Ip);
• check whether the measured pumping current (Ip) and the measured pumping voltage (Up) lie within a specified tolerance range (33) of a characteristic curve specification for a dependence between the pumping current (Ip) and the pumping voltage (Up);
• and
• when the values lie outside the tolerance range (33) of the characteristic curve specification, then adjusting the lambda value (λ) based on the pumping voltage (Up) of the lambda sensor rather than based on the pumping current (Ip) of the lambda sensor (18, 20), and, in an adjusted state, measuring a further pumping current (Ip) of the lambda sensor and, for the self-alignment of the lambda sensor, the pumping current offset (32) is derived from at least one of:
• a further pumping current (Up) for a compensation of a leakage current, a fault current of the lambda sensor and a cable harness belonging to the lambda sensor.