Method and device for identifying and distinguishing a cause of at least one misfire of an internal combustion engine

A method for detecting and distinguishing a cause of at least one combustion misfire of an internal combustion engine, the internal combustion engine having several cylinders, at least one exhaust gas tract, and an exhaust gas sensor arranged in the exhaust gas tract, the method comprising the following steps:

• acquisition of a measurement signal with the exhaust gas sensor over a first period of time, the measurement signal is characteristic of oxygen content in the exhaust gas tract;
• subdivision of the measurement signal into measurement signal sections;
• assignment of the measurement signal sections to corresponding cylinders, whereby cylinder-selective measurement signal profiles are produced that are characteristic of the respective oxygen content downstream of the respective cylinders over the first period of time;
• and
• evaluation of the cylinder-selective measurement signal profiles to detect at least one combustion misfire of the internal combustion engine;
• wherein, when the at least one combustion misfire is detected, an evaluation of the cylinder-selective measurement signal profiles takes place in order to distinguish the cause of the at least one combustion misfire,
• wherein at least one of the combustion misfires is detected as soon as at least one of the cylinder-selective measurement signal profiles exceeds a first threshold value,
• wherein, in order to distinguish the cause of the at least one combustion misfire, at least one of the cylinder-selective measurement signal profiles is compared with a second threshold value, and
• wherein, when the at least one combustion misfire is detected, the one combustion misfire is detected as an ignition misfire if at least one of the cylinder-selective measurement signal profiles only exceeds the first threshold value of the threshold values.

A device for detecting and distinguishing a cause of at least one combustion misfire of an internal combustion engine, the internal combustion engine having several cylinders, at least one exhaust gas tract, and an exhaust gas sensor arranged in the exhaust gas tract, the device comprising:

• a control unit configured to execute a method, the method comprising:
• acquisition of a measurement signal with the exhaust gas sensor over a first period of time, the measurement signal is characteristic of oxygen content in the exhaust gas tract;
• subdivision of the measurement signal into measurement signal sections;
• assignment of the measurement signal sections to corresponding cylinders, whereby cylinder-selective measurement signal profiles are produced that are characteristic of the respective oxygen content downstream of the respective cylinders over the first period of time;
• and
• evaluation of the cylinder-selective measurement signal profiles to detect at least one combustion misfire of the internal combustion engine;
• wherein, when the at least one combustion misfire is detected, an evaluation of the cylinder-selective measurement signal profiles takes place in order to distinguish the cause of the at least one combustion misfire,
• wherein, during the evaluation of the cylinder-selective measurement signal profiles in order to identify that cylinder in which the combustion misfire failed, the cylinder-selective measurement signal profiles can be compared with each other, and
• wherein the combustion misfire failed in that cylinder whose cylinder-selective measurement signal profile has a largest signal deflection compared with the other cylinder-selective measurement signal profiles.

A device for detecting and distinguishing a cause of at least one combustion misfire of an internal combustion engine, the internal combustion engine having several cylinders, at least one exhaust gas tract, and an exhaust gas sensor arranged in the exhaust gas tract, the device comprising:

• a control unit configured to execute a method, the method comprising:
• acquisition of a measurement signal with the exhaust gas sensor over a first period of time, the measurement signal is characteristic of oxygen content in the exhaust gas tract;
• subdivision of the measurement signal into measurement signal sections;
• assignment of the measurement signal sections to corresponding cylinders, whereby cylinder-selective measurement signal profiles are produced that are characteristic of the respective oxygen content downstream of the respective cylinders over the first period of time;
• and
• evaluation of the cylinder-selective measurement signal profiles to detect at least one combustion misfire of the internal combustion engine;
• wherein, when the at least one combustion misfire is detected, an evaluation of the cylinder-selective measurement signal profiles takes place in order to distinguish the cause of the at least one combustion misfire,
• wherein at least one of the combustion misfires is detected as soon as at least one of the cylinder-selective measurement signal profiles exceeds a first threshold value
• wherein, in order to distinguish the cause of the at least one combustion misfire, at least one of the cylinder-selective measurement signal profiles is compared with a second threshold value,
• wherein, when the at least one combustion misfire is detected, the one combustion misfire is detected as an ignition misfire if at least one of the cylinder-selective measurement signal profiles only exceeds the first threshold value of the threshold values.